Alexander Hleb has said sorry for falling short of expectations during his injury-hit season-long loan at Birmingham.
The Barcelona playmaker has suffered a number of fitness setbacks during the campaign, when he was hoping to return to regular first-team football.
Former Stuttgart star Hleb, who has admitted he would relish a return to Germany this summer, is frustrated that he has not been able to shine at St Andrews.
But he is now fit again and he hopes to celebrate his 30th birthday in style on Sunday with three points against Wolves which would virtually ensure Premier League survival.
He said: "It has been difficult. I came to this club with ambition and wanted to give my best for Birmingham City but the injuries have been bad.
"I haven't shown everything that I know I can and I'm sorry for that. I wanted to give more but I can't change what happened.
"But I have enjoyed my time, it's been a new experience here in Birmingham for me.
"I want to say a thank you to everybody linked to Birmingham City. I have been given the opportunity to understand the big history of this good club, I've learned a lot.
"I fully respect the fans and every single player because these people have done a lot for me."
Hleb knows the importance of the clash with Wolves, as he added: "We want to stay in the Premier League.
"I don't care what happens in the game on Sunday and how we do it but we need to win against Wolves.
"It is a very important game. It's my birthday and if we win it will be the best present for me. I'll be doing everything to make sure that happens.
"I believe 100 per cent that we will stay in the Premier League. We're good enough to stay and play in this division."
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