"They face quality and they face pressure," the manager told arsenal.com. "That's what their future is if they stay at Arsenal Football Club.
"First of all, it's an interesting competition because they play against different kinds of football. For us, it is absolutely fantastic to see our players in these circumstances.
"We learn a lot about our players and about their potential. I've seen the home games when I can and of course I get the reports about the away games.
"They've done quite well away from home because they only lost against Marseille in the last minute. We drew 0-0 at Bilbao and we lost 2-0 in Greece [to Olympiacos].
"We now have the chance to qualify against Bilbao and that will be fantastic."