Friday 15 September 2017 11:18, UK
After Arsenal's 3-1 Europa League victory over Cologne on Thursday, we look at four talking points from the Emirates.
Goals from Sead Kolasinac, Alexis Sanchez and Hector Bellerin gave Arsene Wenger's side victory, but it wasn't all plain sailing in the Group H opener.
Here, Gerard Brand runs through what we learned...
Was the system hurting Rob Holding, or was Rob Holding hurting the system? Arsenal's three-man defence suited the youngster perfectly towards the end of last season, but he had a night to forget on Thursday.
Playing on the right of the three, Holding was exposed on numerous occasions by Leonardo Bittencourt, and struggled in possession as Cologne packed their defensive third without the ball.
Holding's first-half stats don't make for good reading: three fouls, no clearances, no interceptions, no tackles won and no blocks. He was replaced at the break by Sead Kolasinac, who levelled the game with a fine volley.
There's plenty of time and opportunity for Holding to learn, however, and he has shown enough potential in his short Arsenal career to suggest his recent form can be excused with the long-term in mind.
Rightly or wrongly, Arsene Wenger is still experimenting with his back line.
He started with a three-man defence and witnessed a Cologne side - who have lost their first three Bundesliga games - stroll into acres on both flanks throughout a poor first 45 minutes for Arsenal.
Boos rang around at half time, which triggered the Frenchman to switch it up.
Interestingly, Wenger himself admitted after the game that switching to a back four allowed Sanchez to push further up the pitch with the help of Kolasinac, whose signing is looking like a shrewd piece of business.
Sanchez was far more involved in the second half. His goal summed up his last 18 months at the Emirates: taking command of the ball, looking up, seeing nobody worth passing to and going for goal instead. It was brilliant, but nothing new.
Nevertheless, the defensive switch aided him. Is that the final straw for Wenger's three-man project?
"When you play Wednesday-Saturday, it is similar to Thursday-Sunday. It is a preconceived idea, football is down to how you perform on the day. Three days is plenty of time to recover."
Those were the words of Wenger in his pre-match press conference, which he reiterated strongly in his programme notes, but how has his Arsenal side coped with Wednesday-Saturday turnarounds in recent years?
Arsenal have faced the Wednesday-Saturday Europe-Premier League turnaround 12 times in the past five seasons, winning eight, drawing two and losing two. Those two defeats came against Chelsea (0-2, away, 2015/16) and Manchester City (3-6, away, 2013/14).
If Arsenal are to show signs of fatigue on Sunday, Wenger may want to remind himself of his pre-match words before using Thursday night as an excuse.
So, just how tired will Arsenal be on Super Sunday against Chelsea? They made nine changes from the side that beat Bournemouth on Saturday, though that selection itself would have been with Thursday night and Sunday's game in mind. With Europa League participation, Wenger is now looking two or three steps ahead.
Bellerin and Nacho Monreal were the only two that remained from Saturday, the former putting in a breathless performance alongside Sanchez. It will be interesting to see how both recover for Sunday.
Chelsea made five changes on Tuesday, coming through 6-0 against Qarabag, and that extra 48 hours recovery could be telling.
Eden Hazard also stepped his return from an ankle injury; he played 32 minutes on Tuesday having played 12 on Saturday, and how Wenger would love to see the Belgian remaining on the bench on Sunday with last season's wonder goal at Stamford Bridge still fresh in the memory.
Petr Cech, Laurent Koscielny, Alexandre Lacazette, Mesut Ozil, Danny Welbeck, Aaron Ramsey and Granit Xhaka did not train with the matchday squad this week, despite all being match fit, so expect to see them fresh for Sunday.
