United's Valencia undergoes surgery on arm

Britain Football Soccer - Manchester United v Leicester City - Barclays Premier League - Old Trafford - 1/5/16 Leicester City's Christian Fuchs in action with Manchester United's Antonio Valencia Reuters / Darren Staples Livepic EDITORIAL USE ONLY.

Manchester United defender Antonio Valencia has undergone surgery after fracturing his arm in Wednesday's League Cup victory over Manchester City.

"Now thinking only in recovery. I want to come back soon and help my team. I'll come back stronger and always optimistic," Valencia said on Instagram.

United have not put a timeframe on Valencia's return but British media suggested he could be sidelined for six weeks. Matteo Darmian is expected to fill the vacant right back spot.

Valencia's injury is another blow to Jose Mourinho's side, who lost centre back Eric Bailly to a knee injury against Chelsea last week and is expected to miss up to two months of action.

United are eighth in the Premier League and trail leaders Manchester City by eight points after 10 games. They travel to face Swansea City in the league on Sunday before hosting Arsenal on Nov. 19.