Seven-time champion Schumacher to retire from F1

(CNN) -- Seven-time world champion Michael Schumacher will retire from Formula One at the end of the season.

The announcement by Schumacher, who originally retired from the sport in 2006 before launching a comeback in 2010, was prompted after he learned he was to be replaced at Mercedes in 2013 by Lewis Hamilton.

A winner of 91 grands prix in a career which has spanned 21 years, Schumacher denied he has chosen to retire because he can no longer compete with the very best in Formula One having managed just one podium finish since coming out of retirement.

"I have decided to retire from Formula One at the end of the season, although I am still able to compete with the best drivers of the world," the 43-year-old told F1's official website.

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"This is something that makes me proud, and this is part of why I never regretted my comeback."

The former Ferrari driver has struggled to regain his top form since returning to racing, registering just 149 points in two-and-a-half seasons back behind the wheel.

"I can be happy with my performance and the fact that I was continuously raising my game during the last three years," he commented. "But then, at some point it is time to say goodbye.

"I said at the end of 2009 that I wanted to be measured by my success, and this is why I had a lot of criticism in the past three years, which was partly justified.

"There is no doubt we did not achieve our goal of developing a car capable of fighting for the world championship in those three years. But then it is also clear that I can still be very happy about my overall achievements in F1."

Schumacher's comeback with Mercedes saw him reunited with team principal Ross Brawn, who he won world championships with at both Benetton and Ferrari.

It is his decade with the Italian marque which cemented Schumacher's reputation as one of the sport;s finest drivers.

In 2000 Schumacher won Ferrari's first drivers' championship in 21 years, going on to clinch the title in each of the next four seasons.

"Already during the past weeks and months I was not sure if I would still have the motivation and energy which is necessary to go on," said the 43-year old German.

"And it is not my style to do anything which I am not 100 percent convinced about. With today's decision I feel released from those doubts.

"In the end, it is not my ambition to just drive around but to fight for victories; and the pleasure of driving is nourished by competitiveness."

Schumacher had been linked with a switch to Sauber to replace the outgoing Sergio Perez, who will take Hamilton's seat at British team McLaren.

Meanwhile Hamilton, the drivers' champion in 2008, has denied his move to Mercedes has been motivated by money.

"It was hard. Really, really hard. It was very, very stressful and then there became a crunch time where there was pressure from the team," the 27-year-old was reported to have said in British newspaper The Guardian.

"There was one deadline and we didn't do anything with it. We just went on to another deadline. But then the decision was made. It really, really was tough but once I made the decision I was so much more relaxed.

"It was not about the offer. I had two offers on the table which were very, very similar. Martin [Whitmarsh, McLaren team principal] asked me what more they could have done. I said: 'To be honest, Martin, it was about the new challenge and a step that I wanted to make.'"

Hamilton also insisted his departure has not created any animosity within the team heading into this weekend's Japanese Grand Prix.

"I have got nothing but love for Martin," he said. "When you are with a team for so long you generally learn to love them.

"I think I will always have McLaren at heart even when I am driving for another team down the line. I will still have a bit of my heart that is McLaren."