Arsenal face perhaps the toughest test of their season so far when German leaders Bayern Munich visit the Emirates Stadium Tuesday for a UEFA Champions League Round of 16 first leg. Ahead of the match, manager Arsene Wenger will face a crucial decision.
Who should play at left-back for the Gunners?
Bayern Munich will enter the two-legged tie as favorites, having lost only two matches in all competitions this season. The Bavarians lead Germany's Bundesliga by 15 points over two-time defending champions Borussia Dortmund and have won their last five league matches by a combined score of 13-0.
According to WhoScored.com, Bayern have held more possession than any team besides Barcelona in Europe's top five leagues. But offensive dominance has been only part of the story. Bayern have conceded just seven goals in 21 league matches this season—and only one in 10 trips away from the Allianz Arena.
In the Champions League group stage, Jupp Heynckes' team suffered an early blip in losing 3-1 at BATE Borisov, but recovered to qualify comfortably along with Valencia.
All considered, Arsenal must produce two nearly flawless performances to progress to the quarterfinals. Avoiding defeat in Tuesday's home match is critical.
Facing Bayern's offensive juggernaut will not be easy. Even with last season's leading scorer Mario Gomez injured for much of the season, Bayern have knocked in 55 league goals this season, an average of 2.6 per match.
Arsenal, meanwhile, have been inconsistent defensively. The Gunners recently recorded back-to-back clean sheets against Stoke and Sunderland but have conceded two or more goals 10 times in the league this season.
Bayern's roster features a number of players who can attack Arsenal's left side effectively. German international Thomas Müller, who has scored 15 goals in all competitions this season, figures to be the primary threat on Bayern's right, while Toni Kroos and Franck Ribery could also move in and out of the formation.
Arsenal left-back Kieran Gibbs is injured and unavailable for the match (via BBC Sport). New signing Nacho Monreal is cup-tied to Málaga, and Andre Santos was recently loaned to Gremio for the rest of the season (via The Guardian).
Thomas Vermaelen, normally a central defender, can play as a full-back. The Belgian captain has been dealing with an ankle problem, but Wenger said Thursday that Vermaelen could return Saturday in the FA Cup against Blackburn.
"He is looking quite good and is possibly back for Saturday," said Wenger (via Arsenal.com). "He should be in the squad."
If he returns, though, Vermaelen might have to slot into central defense. Laurent Koscielny is still recovering from a calf injury that caused him to withdraw from Arsenal's win over Sunderland at the last minute.
Another option at left-back is Bacary Sagna, whose natural position is right-back but performed well out of position as a central defender against Sunderland. In addition, the less-experienced Carl Jenkinson (another right-sided player) and Ignasi Miquel (who is still listed as an academy player) should be available, if needed.
Most Arsenal fans would agree that Santos' departure does not hurt in this situation. Santos had played poorly in his recent appearances. If Vermaelen is healthy, and if Koscielny can partner with Per Mertesacker in the middle, Vermaelen would seem to be the natural choice at left-back (with Sagna playing on the right). His performances at full-back over the past two seasons have been mixed, but he offers the most experience there in the absence of Gibbs and Monreal.
If Vermaelen fails to recover in time, Wenger could have a difficult decision to make.