Yves Lampaert has taken the first yellow jersey, seven seconds ahead of defending champion Tadej Pogacar, as the 109th Tour de France started under clouds, both real and metaphorical, in Copenhagen.

QuickStep-Alpha Vinyl's Belgian rider Lampaert won a damp and treacherous 13.2km opening time trial around the Danish capital in a time of 15 minutes 17 seconds on Friday.

He beat his fellow Belgian superstar Wout van Aert by five seconds, with Pogacar finishing third to make an impressive early statement in his bid for a third consecutive title.

"I have beaten the great Wout van Aert," said Lampaert.

"It's incredible, I never expected that. For now, I don't understand. It's the Tour de France, the best riders have completed the course and I'm in the lead!"

Olympic time trial champ Primoz Roglic and Jonas Vingegaard, two of the main race favourites, conceded nine seconds to Pogacar, while an overdressed Geraint Thomas, who forgot to take his gilet off before the start, finished 18 seconds down on the defending champion.

It was not a great start for the Australian challenge, though, as the country's most likely general classification contender Ben O'Connor, of AG2R Citroen, could finish only 79th, a minute and one second down on the lead.

Michael Matthews, of Team BikeExchange-Jayco, was the best placed, as he came home 17th, 25 seconds behind.

The miserable weather did not put off thousands of fans who turned out for the Tour's Danish debut but the conditions did sum up the mood of many after news of a major anti-doping investigation landed just hours before the first rider rolled down the start ramp.

Europol and Eurojust issued statements confirming that 14 raids at locations across Europe this week, in addition to one at the hotel of Team Bahrain-Victorious on Thursday, were part of an investigation into "possible doping allegations (against) a cycling team participating in the Tour de France".

Bahrain-Victorious, for whom Australian Jack Haig is joint team leader, have denied any wrong-doing and insisted the timing of the investigations into the team, which also included a raid during last year's Tour, were designed to "damage their reputation".

It was another blow to the reputation of the sport too as its biggest event started against unwanted questions.

Copenhagen, the furthest point from Paris the Tour has ever started, had waited an extra 12 months for this day - a knock-on effect from the pandemic and the postponement of Euro 2020 - but when it came the weather was not playing ball.

The main favourites had all chosen early start times in a bid to avoid the worst of it but the heavy showers arrived earlier than forecast and it was towards the end of the day that the roads dried, though only slightly.