Arsenal boss Mikel Arteta wants his side to return to the standards he has set for them as they face a London derby at West Ham.
The Gunners underperformed in a 1-0 Europa League defeat to Olympiacos on Thursday night but advanced into the quarter-finals with a 3-2 aggregate win.
Arteta said after the game that his side would need to improve if they are to progress further in the competition, having been drawn against Slavia Prague in the last eight.
"I think they have a really strong squad and they have a great manager and coaching staff," he added.
"They started the season with some doubts but I know what David is capable of doing.
"Obviously they have a little bit more time during the week to prepare football matches and training, and I think they've been in great form and they're a really dangerous team."
