Arsenal defender Mustafi says Alex Iwobi and his Gunners team-mates must guard against losing their three goals cushion in Moscow when they take on Ahmed Musa's CSKA in Thursday's Europa League quarter-final second leg fixture.
Ever since the final whistle blew at the end of Arsenal's 4-1 first leg win over CSKA Moscow last week, there has been a sense that the Premier League side already have one foot in the semi-final of the Europa League. However, Barcelona were
eliminated from the Champions League from exactly that position of strength against Roma on Tuesday, and Real Madrid also had difficulty converting a three-goal first leg lead into qualification 24 hours later against Juventus.
The situation in Arsenal's quarter-final tie is the same - Iwobi and his gang lead 4-1 after the first leg at Emirates Stadium, and Mustafi
says Tuesday night’s shock has come at the “perfect time” for them.
"I think it came as perfect timing for us, to see that it is football, you are never safe especially when you win at home and have the away game.
"You have to be very careful how you show up and I think the game we saw yesterday was perfect timing for us to show us that we have to be really focused and really concentrated to finish off the job we did in the first leg.
"I did watch it, I thought Roma did a brilliant job. It isn't easy when you lose the first game 4-1, especially against Barcelona, a team who can always score.
"I think they did a brilliant job but it is nothing that surprises me. Now I have been a few years in professional football and I know this happens often."
Wenger's team are the top-scoring side in the Europa League so far this season with 27 goals,
and have won eight games in the competition - more than any other side.