Top seed Carlos Alcaraz has set up a showdown with Jannik Sinner for a spot in the Indian Wells Masters final after defeating Felix Auger-Aliassime.

US Open champion Alcaraz got off to a flying start on Thursday, forcing the Canadian to save four break points before landing an inch-perfect forehand winner to break for a 3-2 lead in the opening set.

Auger-Aliassime grew into the match in the second as the pair traded early breaks, but Alcaraz was able to ramp up the pressure and served it out to secure a first win over the eighth seed and make the semi-finals of the tournament for a second straight year.

"My goal today was to stay in it, and I played probably one of my best matches this season, so I'm really happy," 19-year-old Spaniard Alcaraz said.

"He has a great first serve, and this is the first time I broke his serve, so I'm happy with that. I'm looking forward to playing Sinner again, we've had some great battles."

Earlier, Italy's Sinner beat defending champion Taylor Fritz 6-4 4-6 6-4.

Sinner, 21, was sharp from the outset, riding an early service break and fending off a break point to take the first set behind his solid baseline game.

Fourth-seed Fritz responded in the second, breaking Sinner on set point with a backhand winner that brought the crowd to their feet.

An exchange of breaks kicked off the third, but 11th seed Sinner broke for a 5-4 advantage and blasted a serve Fritz could not handle on match point, the American's backhanded return sailing long to end the engrossing contest in the southern California desert.

"I just tried to play quite aggressively, which I've done," said Sinner, who booked his first semi-final at the Masters 1000 tournament.

"I'm obviously very happy about the performance. Playing against Taylor is never easy. I lost against him two years ago here. He loves the conditions here so I'm very happy that I found a way today."

Fifth-seeded Russian Daniil Medvedev takes on 14th seed Frances Tiafoe of the United States in the other semi.