Borussia Dortmund star Pierre-Emerick Aubameyang has said last season's Champions League finalists must improve ahead of Tuesday's Champions League key showdown at Arsenal.
The Gunners of north London host Tuesday's match as Group F leaders after two wins, while Dortmund are second having bounced back with a 3-0 win over Olympique Marseille following their opening 2-1 defeat at Napoli.
Dortmund laboured to a lethargic 1-0 win over Hanover 96 on Saturday in the Bundesliga to leave them second in the table and Aubameyang said they must be significantly better at Emirates Stadium.
"Playing Arsenal won't be easy at all and we'll have to do better than we did on Saturday," said the Gabon international, who has scored five Bundesliga goals for Dortmund since joining from St Etienne this season.
"We didn't have our usual rhythm and didn't play the high-tempo football we normally do."
While Arsenal's attacking midfielder Mesut Ozil underlined his current form with two goals on Saturday in the 4-1 Premier League win over Norwich, Aubameyang says Dortmund have other Gunners' stars to worry about.
"Ozil is in great form and is crucial to Arsenal's game, but they're a quality side anyway," said the 24-year-old.
"(France striker) Olivier Giroud, for example, is also a very good player, I know him well from my time in France, he's a dangerous striker."
Aubameyang put Dortmund's lacklustre performance down to the toll of the international break with several stars having been away on duty.
"We let the game slip away from us and let Hannover find a way into it," he said.
"I think it was because a lot of our players had played for their national sides and have had long journeys behind them.
"Some of our players have also only just returned from injuries and haven't even been able to train properly.
"I had the impression some of us were already tired going into the game, and it got worse as the match proceeded."