Champions League four burning questions: Should Liverpool drop Alexander Isak? Arsenal set pieces unstoppable?

The Champions League resumes this week in the curious nethersphere. Any table that has the likes of Bayern Munich, Real Madrid and Paris Saint-Germain at its summit has a good chance of being representative of the end product of the league phase five games from now, but equally it feels a little bit like Qarabag's place among the 100% teams might not carry through. For now, it is not entirely clear just how much it matters that Liverpool were beaten in Turkey or Juventus are yet to trouble the win column.

If exactly what's at stake may not be clear, this slate of games still has plenty of intrigue. Can Liverpool end their losing run in Germany? How do two of the most win at all costs clubs in Europe -- Arsenal and Atletico Madrid -- match up? Well those aren't the questions we're addressing... but they are the games. Here's what I'm wondering about.

1. Arsenal vs. Atletico Madrid: Will Gunners keep firing at set pieces?

Now this is a proper test of Arsenal's set piece bombardment. Atletico Madrid can be as aggressive, organised and cynical as Mikel Arteta's side when the ball goes into their box. They might not be quite a match for the street fighting men of Diego Simeone's early days, but when the mood takes them, as it often does on big European nights, they remember how to scrap the old way. Whatever their style, they are also an exceptionally effective team at defending dead balls, conceding the fewest such goals of any La Liga ever-present over the past three seasons. That is quite something when they don't dominate possession to the same extent as other top teams.

Then again, they haven't come up against a team like Arsenal yet. No one has. This is probably the best dead ball team there has ever been, Bukayo Saka and Declan Rice can put their deliveries on a six pence and they are aiming at giants like Gabriel Magalhaes and Mikel Merino. You would think the menace that has resulted in 10 set piece goals in the Premier League already this season might be the result of hours and hours under the tutelage of Nicolas Jover. "Unfortunately with the schedule we don't have as much time as I'm sure Nico would love to have," said Merino.

"We pay attention to every single detail and with the small amount of time that we have we try to make the best out of it for sure." It is that attitude that saw Rice spot the opening that would come against Newcastle if they quickly took a short corner and which has seen Saka set teams up with a string of low deliveries at the near post before hanging one high for when Gabriel might get separation.

"Keep evolving and keep improving," said Arteta of the work that goes into his team's dead ball success. "It's a system that when you put it in place, the system has to learn every single day, every single game to become better and that's in relation to the players that we have, and what we learn from ourselves and as well what we learn from the opposition and try to be as consistent as possible."

Arteta has gone well beyond the confines of football in pursuit of coaching excellence, consulting the likes of former England rugby boss Eddie Jones, Steve Kerr and Sean McVay in pursuit of marginal gains. He is not the only one. Merino is quite the admirer of the NFL.

You can see what he might have learned from hours of watching wide receivers make big plays in his stuttering run before a rise with purpose for the equaliser with Newcastle. Against Chelsea too, the inspiration is apparent in how he uses his hands to drive away from Reece James, getting the run on his defender to meet a corner at the near post and flick in the game's winner.

"I was lucky enough a couple of summers ago to be doing some commercial stuff with a defensive end from the [New Orleans] Saints, Cam Jordan," Merino told CBS Sports. "We spoke a lot about what type of movements he does, how he uses the hands and how he uses his body to get rid of the opponent.

"Mentally, I think you can learn a lot, because in the NFL it's one play at a time and sometimes in football you get carried away by momentum, by the fans or by the result and you have to be focused on the next play. Keeping the focus on the next action and [knowing] what happened 10 seconds ago doesn't matter is the main thing you can take away from the NFL as well."

So long as Arsenal keep evolving when it comes to their most dangerous attacking weapon, pulling in best practice from other sports, it is hard to see how they can be stopped. After all, they're doing all this with players who are better than anyone else at the basics.

2. Club Brugge vs. Bayern Munich: Can anyone stop Kane?

Harry Kane does not seem minded to slow down any time soon. This is the most almighty of tears with which to start a season, 21 goals in 12 matches for club and country. Those goals would be enough to give anyone a headache but this is a player who, particularly at this stage of the season, offers more than just penalty box performance. Take the one game in which Kane did not score, a 3-2 win at Augsburg. Two of Bayern Munich's goals were assisted by their No.9.

Or, indeed, consider his performance on Saturday. Kane didn't just deliver the opener, he ran the midfield, completing 11 long passes, a record for him in any league game, according to Opta. He functioned, as he put it after the game, as "a six, an eight and a 10". The most important number went unsaid. On current form, the only argument that Kane is not the most complete attacker in the sport is the ongoing existence of Kylian Mbappe. For all that Club Brugge performed impressively in beating Monaco last time out, it is hard to see them not falling the way of so many of Bayern's opponents this season.

The question for Bayern is whether this can all last into next spring. The goals almost certainly cannot, at least at the current rate. Kane is one of the best generators and finishers of scoring opportunities in the sport, but even those don't routinely turn 10.8 xG into 18 goals. As for the rest, well anyone who has observed Kane schlep his way through a tournament summer will be skeptical that Kane can keep dropping without his performance levels doing the same.

3. Eintracht Frankfurt vs. Liverpool: Is it time to drop Isak for Ekitike?

Four defeats on the spin has taken Liverpool from wobble to the brink of full blown crisis. In many ways the Champions League offers a respite; no defeat can be quite as cataclysmic as three points dropped in a title race when 24 of 36 teams advance to a knockout game. That means a chance for Arne Slot to reassess matters, to get back to at least some of what worked earlier in this season as well as last.

That probably means taking Alexander Isak out of the firing line. In the years to come the British record $168 million Liverpool paid Newcastle for his services may look like money well spent for a player with all the raw attributes to be one of the best center forwards in the game. Right now, however, putting those attributes to play on the field looks utterly beyond Isak, who has one goal in the League Cup against Championship Southampton and an assist at Chelsea that may or may not have been a mistouch.

In league and European games his output has cratered, less than two and a half shots per 90 minutes and 0.29 expected goals (xG). You would have expected some downward drift after leaving a team who were hell bent on getting the ball to Isak. What you would not have seen coming, ceteris paribus, is a 31% decrease in shot volume, a near 40% dip in xG.

The nadir came in Sunday's defeat to Manchester United, not just the shanked shot from the top of the box and the low drive close to Senne Lammens, but the fact that those were the only two shots he could muster in a game Liverpool were chasing. It said everything that with the equalizer yet to present itself, Slot concluded he was better off with his No.9 off the pitch. At Anfield Isak looked like what he was, a player who did not have a summer to ready himself for his big move.

What is curious is that more time could be afforded to Isak, who has started four of Liverpool's last five games. During the early season winning run Slot was at pains to insist he would keep rotating his side and yet Hugo Ekitike has been afforded few starting minutes to build on what had been an impressive start to the season. Each of his first three games brought a goal and he added to that tally with winners against Everton and Southampton. The France international returns to his former stomping ground in Frankfurt averaging a goal every 139 minutes in all competitions and 0.77 xG per 90, by any definition an impressive transition away from the Bundesliga. It is not one that many of his team mates have found so easy. All of this comparison in output is to say nothing for how much more diligent Ekitike has shown himself to be out of possession.

A trip to the Waldstadion affords Slot an opportunity to indulge the narrative arc, to let Ekitike show Eintracht Frankfurt what they are missing. If Ekitike proceeds to play as he has done in most of the games he has started this season then there is no reason not to keep him in the XI, throwing down the gauntlet for Isak to win his place back at Kirkby. Would swapping striker solve all the issues that beguile Liverpool right now? Not in the slightest, not unless Ekitike can also cover for Virgil van Dijk and bring some dynamism to midfield. It would be a start though.

4. Are Benfica and Athletic Club already in must win territory?

Before their third game of last season's league phase there was little reason to feel worried about RB Leipzig's chances of securing at least a playoff spot. Late goals had seen Atletico Madrid and Juventus get the better of them. Liverpool might have been on the horizon but after that the fixture list really opened up for the Bundesliga side, who would play Pot Three and Four teams in four of their remaining five games. Their xG difference was the 14th best through those two tricky openers and they had created better chances than they allowed. The same was not true as Darwin Nunez's early goal downed Leipzig in the Red Bull Arena but all told, qualification was still an opportunity for them.

And yet Leipzig could never quite rouse themselves to clamber up the table. They were behind the eight ball and, beset by troubles in the league as well, they seemed to conclude that they weren't catching up. Three points was a meagre return. Much the same could have been said of Bologna, who'd also had a pretty tough start to life in Europe, and perhaps even Shakhtar Donetsk. Most statistical projections suggest that nine or 10 points will be enough to get a top 24 spot in the league phase. Teams can, in theory, afford to leave plenty of points unclaimed and rally late on.

Enter Benfica and Athletic. You might think Ajax should be included here but, well, they're not very good. The initial two have been a smidge unfortunate in the start afforded to them by the fixture list, though Benfica really should have beaten Qarabag. After that they were just about the better of the two teams against Chelsea but went unrewarded, now Jose Mourinho takes his team to Newcastle where a defeat might cut them adrift emotionally, if not actually.

Athletic too played pretty well against Arsenal and then had the challenging assignment of a big European night at Borussia Dortmund. They'll have their trip to Newcastle in a fortnight's time, that will be altogether more critical than it ought to be if they wobble against Qarabag like Benfica did. Both these teams would have the quality needed to rattle off a few wins and get back in contention but would it all feel a little too much of a heave with a slow start? We might soon find out.