Understandably, fans have been expressing their disappointment that Welbeck appears to have suffered yet another serious injury as his career at Arsenal has been blighted by a number of injury problems since he joined from Manchester United.
"His injury was with the mentality of the players. You can see on the pitch people know where they need to run, where they need to press, you can see the difference already". "You don't want it to happen but this is our profession".
"Now he is at the hospital". We'll have to wait for updates from Unai Emery after the game but let's pray it's not as serious as it seemed on TV.
Welbeck was making his sixth start under Emery this season and was being linked with a January move.
"It's one big family and we're always going to fight for each other". "We are thinking how he can help us in the future".
"This injury is very big for him, for us and for everyone".
Some of his team-mates were also visibly affected by the incident.
The game only really opened up in the 88th minute when Jeremy Mathieu was shown a straight red for a foul on Pierre-Emerick Aubameyang as the striker raced through on goal.
But Arsenal could not take advantage as Aubameyang blasted the resulting free-kick well over the crossbar.
If Sporting CP is able to snap Arsenal's unbeaten streak, it would pull level atop the group on points, making for a more dramatic run-in over the final two matches.
The Spaniard has gone with some strong line ups in the tournament to date, and in a bid to get the group done and dusted at the first opportunity, he might send out a decent strength side on Thursday.
Emery said after the game: "Lichtsteiner's injury changed our idea on the match, we wanted to change for Eddie Nketiah and give another chance for the striker". But when the match finishes, the first thing they did was ask for him.