Santi Cazorla says Arsenal will not underestimate Marseille when the teams meet at Emirates Stadium on Tuesday.
The French side have lost all four of their games in the Champions League so far but the Spaniard is aware that any complacency may cost the Gunners a place in the last 16.
"We need to understand that it's a vital match"
"The main problem I see is that everyone thinks that it's not going to be an easy game for us to win," said Cazorla. "There is nothing at stake for Marseille because they have zero points but they are going to make things difficult for us.
"It may be tough and if we're not careful we might slip [up] and then we might not be able to get through to the next round.
"We need to understand that it's a vital match. If we get the right result we can automatically go to the next round.
"If we obtained a bad result then it would make things very complicated for us to go to Napoli and win there."