Lewis Hamilton is still on a learning curve in his first Formula One season.
After a nearly perfect season so far, the 22-year-old rookie suffered his first crash during the second practice for this weekend's Monaco Grand Prix, misjudging his speed and going straight into the tire barriers on the first curve of the circuit.
Hamilton was unhurt, but his car suffered some damage on the left side.
"Today was the first time I ever drove a Formula One car around Monaco and it was awesome," Hamilton said in a team statement. "I found out how unforgiving the track can be when I went off in the second session ... I made a tiny mistake and the back of the car slipped a little and that was it. There is just no room for error in Monaco."
Hamilton won in Monaco in Formula 3 and GP2 over the last two years, and is now looking for his first Formula One victory. He comes to the race as the youngest driver ever to lead the championship, after finishing in the top three in his first four races, a Formula One record.
The drivers had a traditional off-day yesterday, with qualifying today. Tomorrow's race is 78 laps.
Hamilton leads with 30 points, two ahead of his teammate, two-time world champion Fernando Alonso and three ahead of Felipe Massa of Ferrari, who won the last two races.
Alonso, the defending champion at Monaco had the fastest times in the first two practices.
He timed 1 minute, 16.973 seconds in his McLaren-Mercedes on his first run on the twisting street circuit, then 1:15.940 in the afternoon.
Hamilton had the second-best time with 1:17.601 in the morning, before his afternoon crash.
McLaren team boss Ron Dennis said Hamilton was "a bit enthusiastic" in the second run.
"I would rather it be in practice than in qualifying or in the race," Dennis said.
Alonso, meanwhile, was glad he avoided the mistakes Hamilton made.
"It's very easy to get a flying lap ruined but that is the challenge for everyone," Alonso said. "I think we are in good shape and with some more fine-tuning we are definitely looking forward to a competitive weekend."
Ferrari's Kimi Raikkonen was fifth in the morning at 1:17.918 and second in the afternoon at 1:16.215.
Massa, who finished eighth in the morning and sixth in the second run, said he is expecting more of his car.
"I didn't manage to exploit all the car's potential, partly because I always had traffic when I was running in the second session with new tires," Massa said. "Unfortunately on this special track traffic can cost you an awful lot of time."
Raikkonen, who won here in 2005, said he was pleased with his runs.
"I am reasonably happy with how things went in the free practice today," the Finn said. "As usual it is too early to draw conclusions to how the rest of the weekend will go because we don't know what our closest rivals have done."
Nick Heidfeld, who finished fourth in the season's first three races in his BMW-Sauber, was third in the morning at 1:17.616 followed by Giancarlo Fisichella, at 1:17.758.