Borussia Dortmund midfielder Shinji Kagawa believes the Bundesliga champions can qualify for the last-16 of the Champions League, despite Arsenal failing to beat Marseille on Tuesday.
Dortmund currently occupy third spot in Group F, having taken only four points from their opening four fixtures.
However, a 1-0 win against Olympiakos has given the German side a renewed hope of progression, although an Arsenal victory would have further helped their cause.
Arsenal would have sealed their own place in the knockout phase with three points at the Emirates Stadium, but were held to a goalless draw by their French opposition.
And, although Kagawa was rooting for an Arsenal triumph, the Japan international realises it is up to Dortmund to force their way back into contention.
"I wanted Arsenal to win, but obviously that didn't happen," he said.
"Nothing changes if we spend all our time worrying about the teams above us, so all we can do is win our next match."