Hakkinen won the F1 title in 1998 and 1999, before retiring in 2001

The Finn, who raced against Button in 2000 and 2001, told the latest issue of F1 Racing: "He may not be quite as quick as a lot of people think he is.

"He's obviously fast, but is he super-fast? I'm not sure he is."

Hakkinen also predicted that Kimi Raikkonen, who replaced him at McLaren when he retired in 2001, will win the world championship this year.

Hakkinen said Button's ability was overstated by the British media when he made his debut with Williams in 2000.

This season will be Jenson's fifth in F1, so there are no excuses any more Mika Hakkinen

The Englishman struggled with Renault in 2001-2, but rebuilt his reputation with BAR last season, and is predicted to do well in 2004.

Hakkinen said: "He made his F1 debut in 2000, for Williams, and straight away the British press started calling him 'the next Senna'. And I have to say that was ridiculous - how could they know?

"OK, it's not surprising that they get excited when a youngster like Jenson gets hired by a team like Williams.

"But the problems start when the youngster himself starts believing what they write. He was a beginner, not a superstar, and I'm not sure he understood that straight away.

"I think he understands it now, though, and it will be interesting to see how he copes with the pressure of being team leader at BAR.

Button has no excuses in 2004, according to Hakkinen

"This season will be his fifth in F1, so there are no excuses any more."

Hakkinen predicted that either a Williams or a McLaren driver would end Michael Schumacher's run of three consecutive championships this season.

"I think Michael probably won't be champion in 2004," said Hakkinen, who beat Schumacher in a battle for the title in 1998.

"Either McLaren driver or either Williams driver could do it - they all have the experience, they all have the speed - but only one of them has the consistency. And that's Kimi Raikkonen."

Hakkinen believes Raikkonen is better than Renault driver Fernando Alonso, who is another of F1's biggest rising stars and rated by some to even better than the younger Finn.

"I don't think Fernando is quite in Kimi's class.

"I haven't seen anything that really justifies the level of hype that has surrounded him so far. He is quick but is he Kimi-quick? Is he Michael (Schumacher) quick? I'm not convinced.

"After all, he and (team-mate) Jarno Trulli tied eight-all in qualifying last year. If Fernando was really quick he'd have done better than that."