Such was the distressing scene a number of his team-mates had to look away before the popular striker was carried off to applause from the whole of the shocked Emirates.
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.
Arsenal have officially qualified for the last-32 of the Europa League.
Arsenal head into their Premier League encounter with Wolverhampton Wanderers having put together a nine-match unbeaten streak in the top flight.
Following on from the US game, which will be the DC United star's only appearance, England will face off against Croatia in their final group match of the UEFA Nations League.
Danny Welbeck just can't catch a break.
Matteo Guendouzi is available once more after his one-match suspension, while Alex Iwobi and Henrikh Mkhitaryan will compete for a spot on the right flank.
And while Nelson may not be a ready-made replacement for Welbeck, Emery says he is keeping a keen eye on his progress.
The injury is the latest in a long line for a player who seems to enjoy very little luck when it comes to his fitness and several of his Arsenal teammates were clearly distressed as the England forward left the field on a stretcher.
Aaron Ramsey of Arsenal crosses during the Europa League match at the Emirates Stadium.
"He's a player I rate really very highly".