Arsene Wenger made light of an injury to Gabriel Paulista, but it is one which could rule him out of some important games for the club.
The new signing was withdrawn after just 36 minutes, substituted with a muscle injury after pulling up, with the rested Laurent Kosicelny replacing him.
He said after the game: "It’s a hamstring. I don’t know, it’s bad enough to come off. It’s usually 21 days, not years!"
Wenger may have quipped about the Brazilian's fitness, but even missing 21 days could be a particularly bad outcome for Arsenal at this important stage of the season.
It could mean him missing four matches. These would be Manchester United away in the FA Cup, West Ham at home in the Premier League, Monaco away in the Champions League, and Newcastle away in the league on March 21st.
At a busy time for the Gunners, it would place pressure on Mertesacker and Koscielny to stay fit, and any injuries to either could be problematic.
With Mertesacker disappointing against Monaco last week, Paulista was beginning to put pressure on him, and fans will hope he is able to return to strengthen the club's options as soon as possible.