Arsenal defender Rob Holding was stretchered off during the Gunners' clash with Manchester United at Old Trafford on Wednesday.
Per James Olley of the Evening Standard, Holding was forced off in the first half with the score at 1-1, prompting a change from manager Unai Emery:
James OlleyNot looking good for Holding. Being helped on to a stretcher. Arsenal don't have a centre-back on the bench.
James OlleyLichtsteiner on. Looks like Emery is staying with the same system but the change means a reshuffle within the centre-back trio. Mustafi into the centre with Sokratis on the left, Lichtsteiner on the right.