Manchester United boss Jose Mourinho admits Romelu Lukaku's impact has surprised him this season.

Mourinho, after seeing Lukaku hit the winner at Southampton on Saturday, says the Belgium international has exceeded his expectations.

"I knew he will always score goals. I knew he would score goals for us than for Everton or West Bromwich Albion, that's logical," said the United manager.

"But I did not expect him to put the ball in the net match after match."

Lukaku has scored eight goals in eight games for United this season, with six now in six Premier League games.