Berbatov has won a Barclays Premier League title, a Carling Cup and played in a Champions League final since moving from Tottenham for £30million two summers ago.
Give us a smile: But Berbatov insists he's happy at Old Trafford
But the Bulgarian striker, who announced his retirement from international football yesterday, has rarely shown the form that persuaded Sir Alex Ferguson to sign him and he scored just 12 league goals in the last campaign.
Berbatov, 29, admitted he has not always been at his best but has no plans to turn his back on the club.
He said: 'I'm sure United will buy a new striker, but I'm still there and that's important. I will try to fulfil my (four-year) contract. Where would I go after United? I've reached the top with them.
'Things could have been better, but they could have been worse too. I have had my moments. People expected me to do things out of this world. It's hard to live up to that.'
And he scoffed at suggestions that his body language betrays a deep-seated unhappiness at United.
He said: 'I can't grin like an idiot on the field. I do not show emotions, but I'm really happy because I am with the biggest team in the world.'
'I do not show any emotions, but I'm really happy because I am with the biggest team in the world.
'I didn't discuss my decision to retire from the national team with Sir Alex, but you know when to say "enough".
'I have had various ailments for several months now. They affect you. I feel tired.
'I took this decision on my own and I started thinking about my future with the national team more than a month ago. I think that this is the right thing to do.'
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