Sunderland defender John Mensah admits frustration over his injury problems this season.

On-loan from Lyon, Mensah has started only four of Sunderland's 20 Barclays Premier League games this season after being hampered by injuries throughout his temporary stay on Wearside.

He said: "I am happy to be with Sunderland, but I am very sad that I have not been able to play because of injuries.

"I don't understand why I have had so many injuries. I need the doctors to tell me why and they are trying to find out what it is.

"I feel I can do well in the Premier League, and of course the African Cup of Nations is a big goal for me and my country.

"The World Cup is also next year, so this should be exciting for me but all I can worry about is why I keep suffering these injuries."