Being bought for $50 million and commanding a seven-figure salary to play for one of the world's greatest clubs does not a happy player make, according to Dimitar Berbatov.

The Bulgarian and Manchester United goalscorer is in good form this season, with six goals in six games but says he struggled through two years of self-doubt to reach that point. A low-key personality isn't always the best way to deal with the glory, pressure and stress inherent to the big stage.

"If people don't know me, they think I am a strange guy – and I am a strange guy, you know," he says. "I'm shy and the people who don't know me don't realize that. I don't like to socialise too much and that's because I am a shy person and have always been like this. I keep my close friends with me whenever I can and that's it. I have difficulty letting anyone else into my inner circle."