As his worried teammates watched, Welbeck was given an oxygen mask by the Arsenal staff that were checking on him.
After a lengthy break in play, and with Matteo Guendouzi and Sokratis Papastathopoulos among the Arsenal players looking most concerned, Welbeck was stretchered off the pitch as the Emirates crowd sang his name.
Mesut Ozil and Gary Neville were among those to tweet a message of support to Welbeck.
Welbeck had earlier in the day been named in Gareth Southgate's England squad for the upcoming friendly against USA and the UEFA Nations League meeting with Croatia.
The Europa League had provided Welbeck with the majority of his football this season, and he scored the only goal in Arsenal's win at Sporting a fortnight ago.
The 27-year-old has had terrible luck with injuries throughout his career and this latest blow will be a huge source of frustration for a popular player who was clearly a part of Southgate's England plans.