Both Arsenal and Bayern Munich will be weakened defensively for the first leg of their Champions League Round-of-16 tie at the Emirates.

The home side will be without a recognized left-back with Kieran Gibbs still out with a thigh injury and recent signing Nacho Monreal cup-tied following his participation in the competition with Malaga. Arsenal allowed Andre Santos to go on-loan to Gremio earlier this month.

It seems certain that Arsene Wenger will elect to move Thomas Vermaelen to the left, where he played for a few games earlier in the season and where he has often been deployed for Belgium. That decision will be complicated for the Arsenal boss, however, if center-back Laurent Koscielny is unable to shake off an illness to partner Per Mertesacker.

For such a crunch match, it seems likely that Koscielny will make it, but if he doesn’t then Bacary Sagna could move into the center of left-back with Carl Jenkinson coming in on the right.

Further forward Wenger looks set to start with the in-form Olivier Giroud up front with Theo Walcott on the right. Lukas Podolski is likely to get the nod on the left to play against his former club, leaving a probable midfield three of Mikel Arteta, Jack Wilshere and Santi Cazorla. Abou Diaby and Aaron Ramsey are the two midfielders who may have to accept a place on the bench.

Bayern’s main concerns before kick-off are also in defense. Holger Badstuber was ruled out with a long-term cruciate knee ligament injury back in December and he will be joined on the sidelines by fellow center-back Jerome Boateng, who begins a two-match suspension. Belgian Daniel van Buyten has been playing alongside Dante recently in the Bundesliga and will again fill in on Tuesday.

In front of the back four, Javi Martinez has recovered from a toe injury that kept him out of Bayern’s Bundesliga victory at Wolfsburg on Friday. The big-money signing from Athletic Bilbao will partner Bastian Schweinsteiger, with Toni Kroos just advanced of the duo.

Arjen Robben has been outspoken about his unhappiness at not being a regular in the side since returning from injury but, despite scoring off the bench last time out, Jupp Heynckes is likely to stick with Thomas Muller on the right of an offensive midfield three.

In the main striking role, Mario Mandzukic’s 15 goals in 19 Bundesliga appearances since his move from Wolfsburg all-but ensures that the Croatian will start ahead of last season’s top scorer Mario Gomez. Third-choice front man Claudio Pizarro is out through illness.

Arsenal (probable)

G: Szczesny

D: Sagna, Mertesacker, Koscielny, Vermaelen

M: Arteta, Wilshere

Walcott, Cazorla. Podolski

F: Giroud

Bayern Munich (probable)

G: Neuer

D: Lahm, Dante, Van Buyten, Alaba

M: Schweinsteiger, Martinez

Muller, Kroos, Ribery

F: Mandzukic

Where to watch: The Champions League round-of-16 first leg will be covered live on the Fox Soccer Channel from 2.45 p.m. ET. A live stream will be available on Fox Soccer 2Go.