Victor Campenaerts has praised his girlfriend as "the hero in this story" after winning a three-way sprint finish to claim stage 18 of the Tour de France.

The Belgian who rides for team Lotto–Dstny timed his attack perfectly at the end of the 179.5km hilly stage from Gap to Barcelonnette on Thursday.

Campenaerts was in the leading trio with Michal Kwiatkowski and Matteo Vercher, with the Belgian biding his time behind the other two riders before exploding into a powerful sprint in the final 200 metres to take his maiden Tour stage win.

The 32-year-old was emotional after the victory as he immediately got on a video call with his girlfriend and child.

"I've been dreaming about this for a very, very long time," an emotional Campenaerts said.

"After the Classics, I had a very difficult time. I had a verbal agreement with the team about extending the contract and I got ignored for a long time and it was really difficult.

"I was on a long altitude camp but my girlfriend was there and she supported me every day, highly pregnant, and I was struggling to finish my training schedules.

"But I changed my mind, I have a bright future now still in cycling. I became a father and I saw only blue skies."

Campenaerts, Poland's Kwiatkowski and Frenchman Vercher broke away and surged ahead about 35km from the finish and the trio kept the pressure on as a group of five riders, including Australian Jai Hindley, attempted to catch up.

But they managed to hold the chasing pack at bay with a comfortable pace until the final sprint when Campenaerts hung back while Kwiatkowski led, constantly looking over his shoulder.

Campenaerts eventually kicked into gear to overtake both riders who gave chase in vain as TotalEnergies' Vercher, who crashed earlier in the neutral zone at the start of the stage, finished second and Kwiatkowski of Ineos Grenadiers third.