Defending champion Carlos Alcaraz fought off swarming bees and Alexander Zverev on Thursday to set up a semi-final clash with Jannik Sinner at Indian Wells.

World number two Alcaraz was stung on the forehead and temporarily forced from the court as a "bee invasion" halted his quarter-final against Germany's Zverev with just two games completed.

He looked none the worse for wear when play resumed after a delay of almost two hours, polishing off a 6-3, 6-1 victory and avenging a quarter-final loss to Zverev at the Australian Open.

Sinner powered into the semi-finals with a 6-3, 6-3 victory over Czech Jiri Lehecka pushing his match win streak to 19.

Sinner's win streak stretches back through last year's Davis Cup finals and includes a perfect 16-0 record in 2024.

In Saturday's semi-finals he'll be out to turn the tables on Alcaraz, who beat him at the same stage last year on the way to the title in the California desert.

Alcaraz said he never imagined his title defense would find him ducking for cover amid a swarm of bees.

He and Zverev were just two games into their match when the bees overwhelmed proceedings, Alcaraz swatting and swiping at the insects after being stung on the forehead.

The bees swarmed the remote-controlled "spider cam" and Alcaraz and Zverev had already run for cover when chair umpire Mohamed Lahyani announced "Ladies and gentlemen, play is suspended due to bee invasion."

A bee expert was summoned and removed the bees clustered on the aerial camera with a live-capture vacuum.

"It was strange, I've never seen something like that on a tennis court," Alcaraz said. "When we ran out of the court, we were watching the bee invasion on the TV and we laughed a lot about it.

"It was funny for me. It's going to be remembered for that, not for the tennis."
 
   - Afraid of bees -

The players were brought back on court to warm up, although Alcaraz insisted bee specialist Lance Davis get rid of some stragglers around the player chairs and equipment.

"I'm not going to lie," Alcaraz said "I'm a little bit afraid of bees."

But he had no more trouble -- with the bees or Zverev.

He said he was pleased with how he managed to stay focused during the delay, as well as with his superb return game against the big-serving Zverev.

Alcaraz said he played "probably one of my best return matches that I've done in my tennis career.

"I put every return in," said Alcaraz, who has gone from strength to strength as he chases his first title since he vanquished Novak Djokovic at Wimbledon last July.

He can expect a tough challenge against Sinner, who captured his first Grand Slam title in Melbourne and has since lifted the trophy in Rotterdam.

In breezy conditions on court two, Sinner was in firm control, breaking Lehecka early in each set and saving the only break point he faced in the match.

"Today was for sure a different situation," Sinner said. "In the beginning was windy, but I handled it very well.

"He's an incredible player with huge potential from both swings. He was serving really well. For sure I'm happy about the performance."

Two other top-10 players clash when fourth-ranked Daniil Medvedev -- runner-up to Alcaraz last year -- takes on number seven Holger Rune -- who saved a match point on the way to victory over 2022 Indian Wells winner Taylor Fritz on Wednesday.

The winner of that match will play American Tommy Paul, who turned the tables on Casper Ruud with a 6-2, 1-6, 6-3 victory over the ninth-ranked Norwegian.

Paul belted 35 winners, saving two break points when serving for the match before clinching it on his second match point.

"It's awesome," said Paul, who had dropped four of his five prior meetings with Ruud. "I'm really pumped with how I'm playing."