Djokovic saw off a first set challenge from Tallon Griekspoor to win 7-5, 6-1 in 77 minutes at the Parc des Eaux-Vives.

Griekspoor, the Dutch world number 27, was the sixth seed at the 28-man Geneva tournament, which serves as a final warm-up before next week's second Grand Slam of the season on the Paris clay.

He had three set points against Djokovic in the first set.

"It was a great win. I thought the first set could have gone his way easily because I think he was a better player for most of the first set," Djokovic said afterwards.

"We could have been having a completely different direction of the match if he converted those set points.

"I was lucky to find some really good serves, and from that moment onwards I really, really played some good, solid tennis."

It was a bridge too far for Griekspoor, who earlier Thursday finished off his second-round match with Denis Shapovalov, beating the Canadian 6-7(7), 7-6(4), 6-3.

The match was called off for the night in the second set on Wednesday due to rain.

Djokovic will face Tomas Machac of the Czech Republic in Friday's semi-finals. The pair have only met once before, with Djokovic winning their contest in Dubai last year. Machac, the world number 44, will be appearing in his first semi-final on the ATP tour.

He saw off 19-year-old Alex Michelsen of the United States 6-3, 7-6(2) in their quarter-final on the Geneva clay. Michelsen knocked out his third-seeded compatriot Taylor Fritz in the second round.

In Thursday's other quarter-finals, second seed Casper Ruud, who won the Geneva title in 2021 and 2022, was to face Argentinian fifth seed Sebastian Baez.