United defender Noussair Mazraoui buried his head in his hands after Raya thrust out a leg to block his shot early in the second half.
Martin Odegaard had a terrific chance at the other end when Arsenal teed up a short corner to the Norwegian but his shot was just pushed over the bar by Onana.
If Raya could perhaps be criticised for conceding from Fernandes's free kick, the keeper salvaged a draw for his side with a stunning double save in the game's thrilling final seconds. He partly-saved a Fernandes shot, and then had to scramble to claw the ball away on the line as it was spinning backwards into the net.
The game finished with the teams level on six shots on target apiece.
United had lost their past four Premier League games against Arsenal — their longest losing run against the Gunners in their league history.
**Reuters**