Borussia Dortmund defender Neven Subotic said his side must step up for Tuesday's opening Champions League clash against an Arsenal team on the rise after a poor start to the season.
Dortmund are back in the Champions League after an absence of nine years, while Arsenal are competing in the tournament for the 14th successive season.
The Gunners have struggled this season after the sale of captain Cesc Fabregas and playmaker Samir Nasri, while injuries and suspensions took their toll before a humiliating 8-2 defeat at Manchester United a fortnight ago.
The Gunners picked up only their first Premier League win of the season on Saturday with a 1-0 win over newly-promoted Swansea when Andrey Arshavin's fortunate goal ensured Arsene Wenger's men took three points at Emirates Stadium.
After the humiliation in Manchester, Wenger says the win has eased the pressure on him and his team.
"It was vital for us to win the game," said the Frenchman.
"When you don't win, you have a deep problem, that's for sure. The longer it lasts, the deeper the problem becomes. As soon as you win things are different."
With that first win under their belts, Arsenal will be keen to get their European campaign off to a good start at Dortmund's Signal Iduna Park stadium, which will be a 80,000 sell-out.
The German champions are also struggling for form as newly-promoted Hertha Berlin poached a shock 2-1 win on Saturday as Dortmund suffered their first home defeat in 18 games.
Dortmund had not been beaten at home in the Bundesliga since the opening day of last season, and Serbia defender Subotic believes they have to step up a level if they are to compete with Arsenal.
"Our performance against Hertha wasn't good enough against Bundesliga opposition and certainly not against a team in the Champions League," said the 22-year-old.
Subotic expects an open game with Dortmund's fleet-footed forwards Shinji Kagawa of Japan and Kevin Grosskreutz up against an Arsenal side known for their smooth passing game, but Tuesday's game is a step into the unknown.
"It is often the case that we will have more opportunities to attack if the opponent is willing to play football, but the Champions League is a first for many of us," he said.
"This is an entirely different level compared to the Bundesliga and we'll see where we stand."