Arsenal defender Laurent Koscielny was sent to hospital with a suspected broken jaw while Sokratis Papastathopoulos left the pitch in pain as boss Unai Emery felt the effects of losing his first choice centre back pairing.
The Frenchman went down clutching his face following an accidental collision with Manchester United striker Romelu Lukaku, who was Man of the Match in United's 3-1 win in the FA Cup fourth round tie on Friday night.
Earlier in the contest Sokratis landed awkward after an aerial dual with Jesse Lingard and was forced off.