Arsenal host Bayern Munich in the first leg of their round of 16 Champions League tie on Wednesday night, and an awful lot has changed since the European champions last travelled to the Emirates.
Last season Arsene Wenger's side were well beaten 3-1, but went on to win 2-0 in Munich in a match that he has credited as the catalyst for their remarkable run of form ever since, as they have transformed from top-four strugglers to title contenders.
Bayern, meanwhile, have pushed on from being one of the best team's in Europe a year ago to become the best team in the world outright, and with the acquisition of Mario Gotze, Thiago Alcantara, Robert Lewandowski and most importantly Pep Guardiola, the club's intentions are clear – to establish the Bayern Munich era much like their manager's Barcelona age before them.
But with both sides on the up, one will receive a huge blow in not reaching the final eight of Europe's elite. Here we take a look at which key players must step up for each side to succeed.
Arsenal's key attacking player: Mesut Ozil
Mesut Ozil's form has dipped in recent weeks – he made four assists and two goals in his first six Premier League games but has just one assist to show from his last six. Arsenal will struggle to beat Bayern if the little maestro has another quiet match. As Jonathan Wilson of The Guardian notes, Ozil's defensive contribution is almost non-existent:
Özil, quite apart from how weary he has looked recently, is probably Arsenal's weakest player defensively (0.9 tackles and 0.2 interceptions per game).
So if he is to be a burden defensively he must make an essential contribution going forwards. There may well be a correlation with Ozil's dip in form and Aaron Ramsey's absence from the side – the duo have been Arsenal's most common assist-scorer combination this season – but with Ramsey's scoring touch missing there is even more emphasis on Ozil to both create and score goals from midfield.
Bayern's key defensive player: Phillipp Lahm
Nullifying Ozil will be an important part of Bayern's game plan, and Guardiola usually does this best by starving the opposition of possession. The 43-year-old manager admitted as much on Tuesday, as Matt McGeehan reports in the Daily Mail:
Ozil's a big talent. We have to control him. The best way to control him is when Bayern have the ball. That's what we're going to try to do tomorrow.
Lahm has been converted to a holding midfield role this season and if he plays in that position at the Emirates he will be Bayern's closest player to Ozil. The Bayern captain is defensively strong but is also Bayern's conductor, drifting across field to link play between defence and midfield. If Ozil's defensive frailties allow Lahm to dictate the game then in turn Arsenal will have very little possession, and Ozil's influence will be limited.
Arsenal's key defensive player: Per Mertesacker
In last season's tie it was the big German who carelessly gave away possession in the build-up to Bayern's opening goal. Since then he has been instrumental in Arsenal's revival and his partnership with Laurent Koscielny at centre-back is one of the best in the Premier League.
Mertesacker faces two possible challenges at the Emirates: If Guardiola selects Mandzukic then he will have to be aware of the runs the striker makes and the space it creates for midfield runners – something Thomas Muller is particularly adept at exploiting.
If Guardiola does not select Mandzukic then Mario Gotze will play in a false-nine role through the middle. He will drift wide to help create overloads on the wings and leave the central areas free at times – and having no striker to mark might be the biggest challenge of all, with midfield runners appearing from all angles at pace.
As the leader of of the back-line Mertesacker must ensure full concentration, particularly towards the end of the match; this season Bayern have scored 24 goals in the final third of games, and conceded just twice.
Bayern's key attacking player: Mario Gotze
Gotze is very likely to start but his role has varied so much this season that it is uncertain where he will play – and it is this uncertainty that makes him so crucial; he is the player most difficult to prepare for.
Guardiola tries to shun comparisons with his Barcelona team but it is impossible to resist the uncanny resemblance to Lionel Messi in both Gotze's style of play and Guardiola's deployment of him. Whether in a wide position or in a central striker role Gotze will have freedom to roam and his remit will be to instigate sudden surges of devastating tempo that unravel Arsenal.
The 21-year-old has six goals and five assists in 16 games so far this season and with Frank Ribery injured, much of the creative onus will be on him. The Gunners don't have great pace in the legs of Mertesacker, Koscielny and Flamini through the middle and Gotze is primed to take advantage of any space he is afforded.