Rublev, who fought back from a set down to beat world number three Alcaraz 4-6, 6-3, 6-2, has struggled to keep his temper under control at times on tour.

The 26-year-old was defaulted in the Dubai Championships in March after a Russian-speaking official said he uttered an obscenity while screaming at a line judge, an accusation that the player denied.

In another match against Alcaraz in the ATP Finals last year, Rublev drew gasps from the Turin crown by repeatedly smashing his racket into his leg before wiping blood off his knee during a changeover.

He destroyed another racket after his shock defeat by Brandon Nakashima in Barcelona last month and had heated arguments with the chair umpire in Madrid last weekend, but the seventh seed said he was making efforts to address the issue.

"I can't believe I was able to stay calm throughout the match," Rublev told Sky Sports after downing defending champion Alcaraz. "I didn't say a word. Even I'm impressed by that."

Coming into Madrid on a four-match losing streak after early defeats in Indian Wells, Miami, Monte Carlo and Barcelona, Rublev looked back to his best against Alcaraz.

He said he had been working hard at staying cool in the heat of battle.

"I want to believe that I've been working on this because if not then I'm stupid," he added.

"After so many years, to not improve on this would mean that something is wrong with my head."

Rublev faces American Taylor Fritz in the semi-finals as he targets a second Masters title heading into the French Open that begins on May 26.