With traction control systems banned and drivers needing to be inch-perfect as they thread their cars around the tight and twisty circuit hemmed in by metal barriers, there is plenty of scope for mayhem in the wet.
"Without traction control it will be a lottery," said Ferrari's Brazilian Felipe Massa, winner of two of the last three races this season but no fan of the most glamorous race on the calendar.
Despite the principality basking under clear skies and brilliant sunshine on Friday, forecasts predict a strong chance of showers on Saturday and Sunday.
Honda's Jenson Button agreed conditions could be difficult, with the painted road markings becoming an additional danger when wet and slippery.
"If you are driving around a normal circuit and you lock up a front in the wet, you can run wide but here there is no run-off area, so you are going to hit a wall," said the Briton of Monaco's special characteristics.
"And in the wet you take different lines. You brake deeper into a corner and run on the outside, so if you get it a millimetre wrong then you are in the wall.
"It's going to be pretty crazy if it's wet, but hopefully we'll get some practice in on Saturday."
HAMILTON FAVOURITE
McLaren's Lewis Hamilton, runner-up on his debut in the principality last year, was fastest in practice on Thursday and a clear favourite to emulate his boyhood hero Ayrton Senna with a Monaco victory.
The 23-year-old, who will be pushed hard by Finnish team mate Heikki Kovalainen, said he was ready for whatever the elements threw at him.
"If it does rain, it's going to be very tricky out on the track for sure, especially without traction control and the aids that we used to have last year...but that's part of the game," the Briton told reporters on Friday.
"They have had races here in the wet in the past years and Monaco is the best track whether it is wet or dry. It'll be a little bit more dangerous in the wet but that's the excitement for me.
"I think tomorrow and Sunday we will be strong but it's going to be very close. The others, especially Ferrari, are very close but I feel we have a very strong package and I'm not worried," said the Briton.
Ferrari have won the last four races but have not won in Monaco since 2001.
Their best bet looks to be world champion Kimi Raikkonen, seven points clear of Massa and Hamilton in the standings, who won in Monaco with McLaren in 2005 and was quickest in Thursday's first practice.
Renault's Fernando Alonso could become the first driver since Senna, unbeatable from 1989 to 1993, to win three times in a row in the principality but that will take something of a freak result given the team's current form.
The former champions have not won a race since 2006 and Alonso's best result so far this season is fourth place in Australia.
BMW Sauber's Polish driver Robert Kubica could be a contender while Germany's Nico Rosberg is very much at home on the city streets in his Williams.
Memories only have to go back as far as Olivier Panis's astonishing win for Ligier in 1996 to serve as a reminder that Monaco can serve up surprises.
Driveability and the talents of the man behind the wheel count for far more than outright speed on the slowest but most atmospheric of circuits. And in the rain, anything can happen
