Manchester United confirm Lisandro Martinez was at Carrington on Wednesday

Martinez's presence at the training complex led to suggestions that the Argentina international was undergoing individual training in the next phase of his recovery from a foot operation.

A statement from Man United on Wednesday confirmed that the centre-back was at Carrington, but the club refused to reveal whether he had taken part in an individual session.

"Manchester United defender Lisandro Martinez watched his teammates train at Carrington on Wednesday, as he continues with the early stages of his recovery from a foot injury," read a statement from the 20-time English champions.

"Martinez has recently spent time in his native Argentina as he recuperates but the 25-year-old is now back at base and was in attendance for the squad's training session, supporting teammates as they prepare for a big week of domestic and European action."

The Argentine has made six appearances for Man United this season, with his last outing coming against Brighton & Hove Albion in the middle of September.

Martinez initially underwent an operation in April to fix the fractured metatarsal that he suffered while representing his club in the Europa League against Sevilla.

The centre-back returned for the start of pre-season, but it was then confirmed at the start of October that he would need to undergo another surgery on the same issue.

Martinez is believed to have aggravated the issue against Arsenal at the start of September, with subsequent scans revealing that the defender's initial operation was unsuccessful in terms of fully addressing the problem.

Red Devils head coach Erik ten Hag recently said that the South American would not be available for selection before Christmas.

However, Man United were handed a huge fitness boost on Wednesday, with Luke Shaw back in full training after recovering from a muscular problem.

Shaw could be back in the squad against Everton on Sunday afternoon, although it would be a surprise to see him return immediately to the first XI, having been out for more than three months.

Fellow defenders Tyrell Malacia and Jonny Evans remain unavailable for selection, but Aaron Wan-Bissaka should be back this weekend, with the Englishman expected to have overcome the illness that forced him to miss the clash with Luton Town before the international break.