The Latest on motorsport's busiest day (all times local):
1:45 p.m.
Formula One champion Lewis Hamilton is in pensive mood at the Monaco Grand Prix - and with good reason.
The three-time world champion has not won any of the past eight races, while his Mercedes teammate Nico Rosberg has won seven of them to take a commanding lead in this year's F1 title race.
As he waited for the driver's pre-race parade to start, Hamilton looked in contemplative mood as he leant against a railing with his headphones on and a hot drink in his hand.
Earlier, he cut an isolated figure in the Mercedes team's motorhome.
Wearing a red cap and sitting on his own at the rear, the British driver sat silently playing with his phone.
Rain fell heavily all morning and briefly abated before returning just before the start of the race, with drivers huddling under umbrellas.
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1:25 p.m.
The Monaco Grand Prix traditionally sees an influx of movie stars from nearby Cannes, where the famous film festival is held.
This year, the events are a week apart and there's a notable absence of big names so far.
However, actor Patrick Dempsey - a long-time star of ''Grey's Anatomy'' and a huge motorsport fan - is in the paddock.
The 50-year-old American has been chatting with Red Bull driver Max Verstappen and Frenchman Romain Grosjean - who drives for the American-based Haas team - before the race.
There is more of a sporting flavor than a Hollywood theme, with basketball stars Chris Bosh (Miami Heat) and Tony Parker (San Antonio Spurs) and International Olympic Committee president Thomas Bach all present.
Bosh, pictured on his twitter feed wearing a Mercedes cap, has expressed his support for Hamilton.
Arsenal soccer star Theo Walcott and Danish tennis player Caroline Wozniacki are also here.
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1 p.m.
The Monaco Grand Prix is all glitz, glamour, blue skies and luxury yachts swaying on the glittering blue Mediterranean sea, right?
That's often the case, but it has been raining all morning in the Principality and fans have been huddling under umbrellas.
With one hour to go before the race, the rain has at least stopped - which might not be good news for Formula One champion Lewis Hamilton.
After finishing third in Saturday's qualifying, Hamilton wrote off his chances of winning - because it's so hard to overtake on the tight and sinewy street circuit - and joked that he would need a downpour to make the race more unpredictable.
