Frenchman Benjamin Thomas ignited the Olympic velodrome on Thursday by claiming a grueling omnium title while New Zealand's Ellesse Andrews charged to an "unreal" women's keirin gold.

In an amazing feat of strength and pace, Thomas, who was fourth in Tokyo three years ago, finished 11 points clear of Portugal's Iuri Leitao with Belgium's Fabio van den Bossche taking bronze.

The omnium is made up of four different endurance races -- the scratch, tempo, elimination and points -- with riders scoring points in each for an overall total.

Thomas's Stunning Omnium Victory

"It was such a crazy race, I still don't believe the medal is mine. I will sleep with it," said Thomas, the 2017 and 2020 world champion. "Today was my day."

He led a pack of five that pulled away with 15 laps left in the opening 10km scratch race, finishing strongly to take the maximum 40 points ahead of Denmark's Niklas Larsen.

But it was Van den Bossche who seized the initiative in the tempo, finishing first to open an overall eight-point lead from Larsen and 10 clear of Leitao.

Van den Bossche came sixth in an elimination duel won by Britain's Ethan Hayter, but still took a 16-point advantage into the final 100-lap race from Thomas.

Determined Comeback and Triumph

However, the Frenchman clawed back into the lead by winning a series of mid-race sprints before coming off his bike with 24 laps to go. Undeterred, he got back on to storm to victory.

"Nothing was broken, thankfully, and I tried to stay calm," he said of the crash. "I kept focused and when I saw in the final 10 laps I could still sprint, I knew today was for me."

With Dutch defending champion Shanne Braspennincx now retired, a new winner was guaranteed in the women's keirin -- one of cycling's most unpredictable disciplines.

Andrews's Remarkable Keirin Gold

Andrews came second in Tokyo and went one better this time, edging the Netherlands' Hetty van de Wouw by 0.062sec with Britain's Emma Finucane taking bronze.

It was her second Paris medal after helping New Zealand to team sprint silver.

"Pretty unreal, to be honest," said Andrews, the current world champion.

"The silver was an amazing way to start our Games as the New Zealand team, and to top that off today with a gold is incredible.

"To be honest, my plan from the start was to respond and react to everyone else, and hopefully that would put me in the right position coming into the bell (last lap)."

Invented in Japan in 1948, the event involves riders lurking behind a motorised pacemaker before exploding in a sprint to the line over the last three laps.

Andrews was the first to make the move in the final and while Finucane attempted a comeback, the New Zealander was too strong.

"To get a bronze medal, it literally feels like gold to me because I left everything out there on the track," Finucane.

In other racing, Dutch star Harrie Lavreysen cemented his status as heavy favourite in the men's sprint, cruising into the semi-finals.

The defending champion shattered the world record in qualifying, stopping the clock at 9.088sec, and swept past Poland's Mateusz Rudyk.

Australia's Matthew Richardson, who briefly held the world record this week before Lavreysen pounced, also made the grade, beating Japan's Yuta Obara.

Britain's Jack Carlin and Lavreysen's teammate Jeffery Hoogland rounded out the final four.