Carlos Alcaraz said he had to go on the offensive to protect his injured ankle after beating Brandon Nakashima 6-2, 6-4 on Sunday to reach the Japan Open semifinals.
The world No 1 hurt himself during his opening match in Tokyo and he admitted after his next outing that the injury had worried him and was on his mind on the court.
The Spaniard again played with strapping showing above his left sock but it did not appear to trouble him as he brushed aside American world number 33 Nakashima with a brutal display of power tennis.
Alcaraz will face Norway's world number 12 Casper Ruud in Monday's semifinals and he said he was "still thinking about the ankle".
"I had to play more aggressive than normal because I just want to let him run much more than I do in the match," said Alcaraz.
"You can see that there are some times that I can't go as fast as I want, I'm just taking care about the steps I'm doing in the match.
"That's why sometimes I was playing really big shots, because I didn't want to run from side to side," he added.
Alcaraz had his service broken three times in his previous night's win over Belgium's Zizou Bergs.
He gave Nakashima no such help and did not face any break points as he stayed on the front foot all match.
Alcaraz is playing in Japan for the first time and he treated the crowd to some outrageous shots that grew gasps from the packed stands.
"First of all, I'm a huge fan of tennis, and seeing these kinds of shots, if it comes from me or not, I just enjoy," said Alcaraz.
"Tonight there were a few of them that I was like 'that was a really good one'."
Alcaraz said the love he is receiving from the Tokyo crowd is mutual.
"Really grateful and really happy with the atmosphere that they're creating," he said.
"I just try to play in a style that I like them to be entertained watching the match."
Alcaraz's semifinal opponent Ruud beat Australian qualifier Aleksandar Vukic 6-3, 6-2.
World No 5 Taylor Fritz will play fellow American Jenson Brooksby in the other semifinal.
Fritz, the No 2 seed, came through a tough quarterfinal against another American, Sebastian Korda, winning 6-3, 6-7 (5/7), 6-3.
Brooksby beat the No 3 seed, Denmark's Holger Rune, 6-3, 6-3.
Fritz, who beat Alcaraz this month at the Laver Cup, said he had struggled with the weather in Tokyo, with temperatures around 27C for his late morning match.
"I wasn't expecting it to be that hot and humid," he said.
"Tough to play in that heat and play a lot of physical, long points."