Guillermo Varela is expected to return to training soon. Alex Grimm/Bongarts/Getty Images

Guillermo Varela, on loan at Eintracht Frankfurt from Manchester United, has suffered another injury setback.

Varela, who had undergone surgery to remove a screw left in his ankle following surgery in September, had to undergo a further operation earlier this week.

He is expected to return to training soon having struggled in the two matches he played after the screw was removed.

"It caused him problems repeatedly. He gave it his all, but he was in a lot of pain," Frankfurt coach Niko Kovac told reporters.

"It shows his character that he wanted to give it his all for team and club.

"The wound must now heal, and then the stitches will be removed. This takes eight to 10 days."

Varela will be one of several players missing when Frankfurt travel to leaders Bayern Munich on Saturday.

Mexico international Marco Fabian and defender Jesus Vallejo will also be missing for a team that has now lost four matches in succession.