Michael Schumacher was a young man filled with doubts when he started his Formula One career.

Twenty years later, he has amassed more triumphs and titles than any other driver in the sport's history - and has, as he said on Thursday, few regrets.

On the anniversary of his debut at the 1991 Belgian Grand Prix, he admitted he was awe-struck when he arrived to compete for the fledgling Jordan team against the great drivers of the era.

At the same news conference, his successor as Germany's top driver and world champion Sebastian Vettel admitted he discovered the legend of 'Schumi' as he played with his toys at kindergarten.

On the weekend of Schumacher's debut, he was only four years old.

After 91 wins, seven world titles, 154 podium finishes and 68 pole positions -- and aged 42 -- Schumacher showed he was no longer daunted by any occasion as he faced a news conference on the eve of this weekend's Belgian Grand Prix.

Schumacher said: "I was doubtful whether my quality was good enough to compete with these guys.

"You see them as untouchables -- especially in those moments where you had (Ayrton) Senna, (Alain) Prost, (Nigel) Mansell and so on. I didn't really think I could match them.

"But, after getting the first experience, coming over here (to Spa-Francorchamps) and driving the car, I sort of quickly picked up the confidence that it was possible and from there on we all know.

"At the end of the day we are all humans, we all have limits and you drive within those -- and there is no reason why it is impossible to beat those guys in the past and neither these guys that are here right now.

"That's the good thing about Formula One. It is always a challenge and it is always a motivating challenge that is great fun."

The veteran champion, now with Mercedes, admitted also that he had never expected to be racing for so long.

Smiling broadly, he said: "Well it is an unusual situation and certainly not something to be expected from the beginning, but now I am proud to be here.

"As I often call it, it's my living room (the Spa circuit) and a very particular place where lots of things, great things and special things, have happened. It is obviously a perfect scenario to celebrate this moment."

Asked if he had any regrets, following a career punctuated by moments of high drama and controversy, he said: "Certainly I guess in every person's career, you look at it and you think well, what has happened.

"You take a summary, you almost make an account and I have to say in my case, taking the 20 years, taking everything that I've been doing.... certainly, going backwards, I would do certain things differently.

"But then in life you have to make some mistakes in order to understand it is a mistake. I don't have many regrets and overall, I certainly feel very excited and proud of what has happened."

Vettel, who was four when Schumacher qualified seventh for the 1991 Belgian Grand Prix, said he first became aware of him when he played with toy cars.

"I remember the first time I went to Hockenheim with my father to see free practice," he said.

"We went all the way down to the first chicane. It was raining like crazy and Michael had this yellow Benetton at the time.

"To see a Formula One car and then to see Michael passing. He was probably just on an installation lap, nothing spectacular, but it was really very special. Unfortunately, nobody else went out because it was raining so hard.

"There were only a couple of cars, but that was the first time that I remember. Obviously, after that there were a lot of races. When I was go-karting, Michael was sort of all the kids' hero.

"When we had this race in Kerpen at the end of the season, he handed over the trophies and it was very special to see him, to meet him, to shake his hand and to get our trophies presented by him.

"There are some pictures from that time and to imagine now, to know what happened in the past and to see today that we are racing against each other is quite crazy.

"Obviously, I have a lot of respect. It's very special to me. As I said, he was the hero of my childhood.

"Of course, I can't give him too much credit now, but I think he's an OK driver..."