MotoGP world champion Valentino Rossi was out in a Ferrari racing car again on Thursday, apparently set on establishing once and for all whether he can hope for Formula 1 glory. The 26-year-old motorcycling star was completing laps of the Ferrari-owned Mugello track in about 58 seconds, compared to a circuit record of 55.99 seconds set by seven times world champion Michael Schumacher last year.

According to unconfirmed sources, Rossi drove a few laps even faster and showed particular skill on the curves, which he knows well as he has raced motorbikes round them in MotoGP Italian Grand Prix races .

On Wednesday, Rossi spent the day at Ferrari's other test track at Fiorano, near the car maker's headquarters in Maranello .

There has been persistent speculation in the media that Rossi, who has now won five successive titles in motorcycling's top class, could some day race Formula 1 cars for Ferrari .

Rossi has frequent contact with the Italian Formula 1 team but is cagey about his intentions in interviews. Meanwhile, Ferrari Chairman Luca Cordero di Montezemolo has frequently said the door is open for Rossi .

Several big names in the Formula 1 world, including Italian driver Giancarlo Fisichella and his boss at Renault, Flavio Briatore, give short shrift to talk of Rossi entering Formula 1 .

They say the sport requires too much training for someone to start in their late 20s and hope to be successful .

But Italian sports fans - along with sponsors and marketing people - are thrilled by the idea that Rossi might try to be the first Italian driver to win a title in a Ferrari since Alberto Ascari in 1953 .

Rossi, who has little left to prove in MotoGP, is also believed to be attracted by the challenge of successfully making a switch which only one man, Britain's John Surtees, has ever done before .

Surtees won four world motorcycling titles before switching to cars in 1960. In 1964, at the age of 30, he won a world title driving a Ferrari .

Rossi recently signed a contract to race another year with his current team, Yamaha, but after that his future is uncertain .

Some fans see him racing for Ferrari in 2007, when Michael Schumacher is expected to retire .

Rossi's third set of tests with Ferrari came two weeks after Schumacher tried his hand at steering a MotoGP motorcycle round the same track near Florence .

The seven-times world champion, fresh from his worst Formula 1 season since joining Ferrari, completed 40 laps on Ducati's Desmosedici bike in an unannounced test apparently aimed merely at satisfying a whim .