Monaco Grand Prix
Dates: 22-25 May Coverage: Radio 5 Live and BBC Sport website
Hamilton is third in the drivers' standings after five races
McLaren star Lewis Hamilton says the Monaco Grand Prix could turn into a "disaster" if rain falls in the Principality this weekend.
"It will be especially difficult here in the wet, especially this year without traction control," he said.
"Pedro de la Rosa (McLaren's test driver) made a comment at the last test that it is incredibly difficult to get to full throttle here in the wet.
"With this circuit being so tight, I think it's going to be a disaster."
Countryman Jenson Button has also voiced his fears about track safety should the weather turn nasty.
"Looking at the forecast, it appears it's going to be pretty awful," said the Honda driver.
"With the white lines going up to Casino Square, if you touch one you've a big chance of putting your car into the wall.
"So it's going to be pretty intense, and you just hope we get some practice in before the race.
"The last thing we all want is to be barrelling into Casino with no practice in the wet."
Even in the dry conditions on Thursday, the Renault duo of Fernando Alonso and Nelson Piquet both lost their rear wing, sliding into the barrier as they exited Sainte Devote.
Hamilton posted the quickest time throughout practice, with the 23-year-old Briton aiming to go one better than his second-place finish of a year ago.
He was comfortably fastest by almost 0.4 seconds from the Williams of Nico Rosberg.
"I simply love Monaco and enjoy every single moment I get to spend on the track," said Hamilton, whose lap of one minute 15.140secs was almost 0.6secs quicker than Alonso's pole position of last season.
"The car felt great almost immediately, and I was able to show a good pace from the very beginning.
"There is a long way to go, but I enjoy this so much and we will work hard to continue making progress."