Seven-times world champion Michael Schumacher came out of retirement on Tuesday to set the fastest lap in testing for Ferrari at Barcelona's Circuit de Catalunya.
The 38-year-old German, who will also be in action on Wednesday at the Spanish circuit, has no intention of returning to Formula One racing after quitting at the end of 2006 however.
Champions Ferrari have described the test as "half for pleasure, half for technical reasons".
Formula One's rules are changing next year, with traction control and other so-called 'driver aids' being removed, and Schumacher can give useful input as a driver who has raced cars with and without the systems.
Schumacher topped the unofficial timesheets, completing 64 laps in the F2007 car with a fastest lap of one minute 21.922 seconds. The circuit Web site (www.circuitcat.com) said 3,000 spectators attended the session.
The first test since the end of the season last month was also Schumacher's first serious outing in a Formula One car since the Brazilian Grand Prix of October 2006.
"It looks as though he's got talent. He will make his way to F1," quipped Red Bull's David Coulthard, at 36 the oldest active driver in Formula One, at the reappearance of his rival.
Ferrari's regular test driver Luca Badoer was second fastest, in 1:22.129, with McLaren's Spanish test driver Pedro de la Rosa third in 1:22.687.
Briton Gary Paffett also tested for McLaren, who have yet to name a replacement for departed double world champion Fernando Alonso.
Quadruple Champ Car champion Sebastien Bourdais of France made his debut as an official Toro Rosso driver while other teams tried out a variety of new faces.
Red Bull had promising young Indian Karun Chandhok, a race winner in the GP2 support series this year, in their Renault-powered car. He completed 39 laps and was 18th out of the 20 drivers present.
"For me, it's a huge thing -- for any driver Formula One is the ultimate ambition," the 23-year-old told Reuters Television.
"To have your first Formula One test you know, gets my foot in the door and allows me a chance to see how it's really like at the pinnacle of the sport."
He shrugged off comparisons with compatriot Narain Karthikeyan, who became the first Indian to drive in Formula One when he raced for Jordan in 2005.
"Of course people in India will always compare but I just do what I have to do, I have my own career," said Chandhok.
"At the moment it's on the way up for me -- I'm here today testing a Formula One for the first time and that's all I really care about."
Force India, formerly Spyker, tested with Dutchman Giedo van der Garde and Spaniard Roldan Rodriguez propping up the timesheets in 19th and 20th places respectively.