Mikel Arteta has acknowledged that Arsenal must overcome their injury problems in defence if they are to maintain their challenge in four competitions. Arteta spoke after ­revealing that William Saliba is a doubt for the first leg of the Carabao Cup semi-final against Chelsea on Wednesday.

Saliba and Leandro Trossard did not feature in the FA Cup victory against Portsmouth on Sunday. It was widely thought both had been rested. However, Arteta confirmed on Tuesday that the France defender could miss the game at Stamford Bridge because of an unspecified injury, while ­Trossard is also a doubt.

Piero Hincapié and Riccardo ­Calafiori both remain out with groin and muscular injuries respectively, while Cristhian Mosquera continues to make progress on an ankle injury and is not expected to return until next month.

That means Arsenal could once again be forced to field Christian ­Nørgaard at centre-back against Chelsea after the Denmark midfielder filled that role at Fratton Park. Declan Rice is not expected to deputise at right-back like he did against Brighton last month with Ben White available again.

Asked if defensive injuries could be the issue that undermines Arsenal’s hunt for silverware this season, Arteta said: “Yes, because we...