Danny Welbeck scored the 77th-minute victor, which gave Arsenal sole possession of first place in Group E. The Gunners haven't lost in their last 14 matches and have found their form under manager Unai Emery, a three-time victor of the Europa League with Sevilla.
The 27-year-old has been troubled with knee problems in the past but has managed five goals in 16 appearances for the Gunners this term.
"Danny remains in hospital and will continue to be assessed".
"His injury also [impacted] the mentality of the players, because they looked and saw it's a big injury".
"The worst news tonight is these injuries", the Spaniard told a media conference. We are going to wait [for updates].
"But when you are playing football in competitive matches it can happen".
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When police arrived, Bruns was found unconscious and unresponsive in a bedroom with no obvious signs of trauma. Bruns pleaded not guilty in May and faced a maximum of 15 years in prison if convicted.
"Danny is a tough lad, so if he's on the floor, I know it's something serious".
But it is believed that Welbeck broke his leg - something which is likely to keep him sidelined for the remainder of the season - based on the reactions of the players around him.
"This injury is very big for him, for us and for everyone".
Former Arsenal ace Perry Groves believes the club should offer Welbeck a new deal.
"The best for him is now to think for the person", Emery said.
As the Lithuanian referee Ged Mazelka blew for half-time following a period of shapeless, scrappy play the only thing one could really say about the opening 45 minutes was to wish the popular "Welbz" well.