LONDON: Arsenal manager Unai Emery says striker Pierre-Emerick Aubameyang will be ready to start Thursday's Europa League quarter-final first leg at home to Napoli after illness kept him on the bench for their past two games.

"He had a small problem and has taken antibiotics for his illness," Emery told a news conference on Wednesday. "That's the main reason he didn't start those matches. For tomorrow he's getting better and can start or can play after."

Emery is also waiting on late fitness tests for central defender Laurent Koscielny and midfielder Granit Xhaka.

The visit of Carlo Ancelotti's Napoli, a distant second behind Juventus in Serie A, represents a big step up in class for Emery's Arsenal in the competition.

The London club will be desperate to travel to Italy with a positive result from the Emirates, having struggled past BATE and Rennes in the previous rounds after losing the away legs.

"Carlo Ancelotti is top. He has experience in all the competitions, in all the countries. His coaching career is amazing," Emery said.

"This is a big-level match, and the level we want to play. It's a very big test for us."

Striker Alexandre Lacazette said Arsenal must respond after losing to Everton in the Premier League last weekend -- a result that left them outside the top four in the race to qualify for next season's Champions League.

"On Sunday we played badly, all the team," he said. "We didn't do what the coach asked us, but we still have confidence."

Napoli also struggled in their Serie A game at the weekend, drawing 1-1 against Genoa, and Ancelotti said he hopes the result will have served as a wake-up call to his players.

"It was an unexpected performance, which rings alarm bells," he said.

"We'll find things very difficult if we play like that in London. We've not yet spoken in detail about that game. I don't want to talk about a mental dip."