Joel Campbell believes Arsenal face their "most important game of the season so far" against Olympiacos, as the English side travel to Greece looking to qualify for the knockout stages of the Champions League.

Arsene Wenger's squad go on the road knowing they have their destiny in their own hands – if they win by any other score than 1-0 or 2-1, they will make the knockout stages of Europe's premier club competition for a 16th season in a row.

Goals, therefore, are going to be crucial for the visitors, who lost 3-2 at home to Olympiacos in September. 

Campbell scored the first for Arsenal in their 3-1 home win over Sunderland in Premier League action on Saturday. However, that was just the second time in their last six outings that they have found the net more than once in a game.

"[The win over Sunderland] was a good result for the team," Campbell told the club's official website.

"We got the result and that's what we wanted. Now we have to prepare mentally and physically for Wednesday's game because it will be very difficult.

"We already played against Olympiacos at Emirates Stadium. They are a great team, a great rival and especially because they play at home.

"It is the most important game of the season so far. It will be a cup final and we have to win to continue in the Champions League."

The Costa Rican also knows how tough it will be playing at Olympiacos' Karaiskakis Stadium, as he spent the 2013-14 season on loan at the Greek team.

"In the Pireo [Karaiskakis Stadium] it is very difficult to get points but it is the last game of the group stage and we will give our best," Campbell added.

Arsenal's record away to Olympiacos does not make for pretty reading - they have lost three times against them since 2009, although on each of those occasions they had already qualified.

This time, though, the match will decide who goes through alongside Group F winners Bayern Munich. Whoever misses out on second place will go into the knockout stages of the Europa League instead.

Felipe Pardo was one of Olympiacos' goalscorers when they won at the Emirates Stadium, but has not played in their last three games due to a calf injury.

Arsenal's midfield anchors Francis Coquelin and Santi Cazorla have been ruled out until well into next year, although Aaron Ramsey has made his return to the starting side in recent weeks and scored at the weekend.