DORTMUND, Germany // Borussia Dortmund, the Bundesliga champions, will make their return to the Champions League after more than eight years when they host Arsenal in Group F tonight.
Dortmund's build-up has been overshadowed by the loss of their 18-game home unbeaten run, which ended on Saturday when promoted Hertha Berlin won 2-1.
But their problems pale in comparison to Arsenal, who have endured a tough start to the season. Only a goalkeeping blunder from Swansea City's Michel Vorm allowed Arsenal to earn a 1-0 win on Saturday, their first victory of the Premier League season.
"The confidence is back now," Arsene Wenger, the Arsenal coach, said. "We just had not won yet in the league and that had played a big part in our heads."
It was Arsenal's first outing since an 8-2 humiliation at Manchester United before the international break. Wojciech Szczesny, the Poland goalkeeper, was the subject of some gentle teasing from Dortmund's Polish internationals after that defeat, but has refused to let the words from Robert Lewandowski, Jakub Blaszczykowski and Lukasz Piszczek affect him.
"After the game, I hope I will be the one who comes out on top," said Szczesny, who was outstanding in Poland's 2-2 draw with Germany. "They can't get in my head, I will be focused."
Juergen Klopp, the Dortmund coach, said on Sunday he had "no anticipation" for the Champions League following the defeat the day before, but added, "surely it will come."
Mario Goetze, the influential playmaker, was suspended for Hertha's win, after a red card from Dortmund's previous game at Bayer Leverkusen, but he will be available against Arsenal.
"Sometimes in such a game you need a knot-picker," said Klopp, highlighting the 19 year old's importance to his side.
Arsenal are aware of the damage Goetze can do. German media say the Premier League side had a €40 million (Dh201m) offer turned down for the Germany international in the transfer window.
Arsenal did bolster their defence with the arrival of Per Mertesacker, the Germany defender, on the final day of the transfer window. The former Werder Bremen captain knows how it is to play in front of the "yellow wall" of fans in the south stand of Borussia's Signal Iduna Park, which is second only to Barcelona's Camp Nou in Europe in terms of capacity. It can hold 80,720 fans.
Fellow new signings Mikel Arteta, Yossi Benayoun, Andre Santos and Park Chu-young could also make their Champions League debuts for Arsenal, though midfielder Aaron Ramsey has an ankle injury.
"In our job, momentum is vital. We just want to play to win," Wenger said. "When you look back when we travelled to Udinese [for the Champions League play-off], everyone expected us to win the game, and we did. We want the same against Dortmund."
Dortmund's Neven Subotic feels Arsenal's open game may suit the home side.
"It's often the case that we have more attacking opportunities when the opponent wants to play football," the defender said. "But it's the first time in the Champions League for many of us. It's a whole other level to the Bundesliga, and we'll see how we do."