Manchester United midfielder Shinji Kagawa has admitted that his performances must improve or he is unlikely to have a long-term future at Old Trafford.

Kagawa has featured in just one Premier League game under David Moyes this season, but was brought off at the interval during last weekend's 2-1 defeat to West Bromwich Albion.

The Japanese international has declared that he was upset to be hauled off at the interval, but vowed to take that decision as a wake-up call to work harder.

He told The Mirror: "In that sense, I was disappointed to have been substituted.

"Sure, I wasn't involved that much, I didn't touch the ball enough, but I was trying to be patient so I didn't feel that bad. However, I have to take this like some kind of message from the manager.

"I need to improve or I can't survive at this club. I have to take this in a positive way and try to do my best."

The 24-year-old has been restricted to three starts in all competitions this season, leading to speculation that he could be sold next summer.