Alcaraz and red-hot Medvedev set up Indian Wells final showdown
In a rematch of their thrilling U.S. Open quarter-final that Alcaraz won in five hard-hitting sets en route to winning the title, Alcaraz needed to save a set point in the opening frame against Sinner before reasserting his control.
Sinner, who ended Taylor Fritz's title defence in the quarter-final, got the first break for a 2-1 lead but Alcaraz broke at love to draw level at 4-4 before going on to grab the tightly-contested frame.
In the second set, Alcaraz stepped up the pressure, often having Sinner scrambling around behind the baseline. He broke early for a 2-0 lead and was well on his way after a perfectly-weighted lob landed just inside the baseline for a 3-0 lead.
From there, Alcaraz relied on an array of shots and raw power to turn what had been a close encounter into a rather comfortable victory to improve to 3-2 against Sinner.
Alcaraz will now turn his focus to Sunday's showdown with fifth seed Medvedev where a victory would return the Spaniard to top spot in the world ranking for the first time since January.
In the early match, Medvedev squandered seven match points before finally getting past Frances Tiafoe (25) 7-5 7-6(4) to secure a place in his first Indian Wells final.
"Always better to finish on your first match point and not on the eighth," said Medvedev. "But that's what makes tennis also a fun sport, and I'm just really happy that I managed not to lose this match and not to have regrets, nightmares, whatever."
The victory extended what has been an impressive run for the Russian, who has won 19 consecutive matches and is one victory away from adding another title to the ones he collected in Rotterdam, Doha and Dubai over the last month.
Medvedev had a glorious opportunity to grab an early break until Tiafoe, who entered the match having not dropped a set in Indian Wells, impressively stormed back from 0-40 in the fifth game of the opening set to hold serve.
But Medvedev made the most of his next break point when he desperately swatted the ball from near his toes from where it clipped the net cord and dropped inside the line to pull ahead 6-5 before going on to serve out at love to take the set.
Medvedev then struck an unbelievable forehand pass down the line to break Tiafoe in the opening game of the second set and five games later turned aside the first break point he faced all day and grabbed what looked to be a comfortable 4-2 lead.
But Tiafoe did well to save three match points on serve to pull within 4-5 and then levelled the set a game later when Medvedev double-faulted on the second break point he faced.
TRYING TO HAVE FUN
Alcaraz said he is unfazed by the pressure of being perceived as a favourite after his meteoric rise to the top of tennis, adding that he is not distracted by the lure of being world number one and simply trying to enjoy every match.
"It doesn't change too much for me," Alcaraz told reporters. "I don't think about that I'm the favourite in every match. I don't think about that I have to win every match.
"I just have goals in my mind, I have things that I have to do, and that's all I think about. I try to enjoy every match. I'm not thinking about anything else.
"I know if I win tomorrow I'm going to be the number one. I will try not to think about that. I have to make everything perfect. That's all I'm going to think about tomorrow."
Medvedev said his second-round win over Alcaraz at Wimbledon in 2021 - the only prior meeting between the two - was no gauge for their showdown on Sunday.
"He was definitely not the same player as he is right now," Medvedev said. So in a way it's going to be like a first match between us in terms of how we're going to go tactically or physically or tennis-wise.
"He's amazing, he has amazing skills which are tough to compare to anyone... It's going to be great fun to play against him."