Japan's Kei Nishikori withdrew from the ATP Miami Masters with a left groin injury on Friday, shortly before he was to meet world number two Novak Djokovic in the semi-finals.
The injury ended Nishikori's sparkling run at the hardcourt tournament -- where he beat world number five David Ferrer and Swiss great Roger Federer in the fourth round and quarter-finals.
It also throws into doubt Nishikori's participation in Japan's Davis Cup World Group quarter-final clash with holders Czech Republic, to be held in Tokyo from April 4-6.
"I don't know if I can play or not," Nishikori said of Japan's first Davis Cup quarter-final tie under the tournament's modern format. "I will try."
Nishikori broke the news of his Miami withdrawal on Twitter and Facebook.
"Very sorry to say that I have to pull out today," he said. "Very disappointed and I am obviously very sorry for any fans that wanted to come out for this match."
The 24-year-old Japanese player rallied from a set down to upset Federer 3-6, 7-5, 6-4 on Wednesday night to reach the second Masters semi-final of his career.
He had saved four match points to beat Spain's Ferrer 7-6 (9/7), 2-6, 7-6 (9/7) in the fourth round.
"For me it was my biggest tournament in a couple of years, to reach a semi-final of a Masters," a dejected Nishikori said in a hastily convened press conference. "It's really sad. I was really playing well."
His withdrawal gave Djokovic a walkover into Sunday's final, where he'll face either world number one Rafael Nadal or Czech Tomas Berdych.
Djokovic is in the Miami final for the fifth time, and will be seeking a fourth title to go with those he won in 2007, 2011 and 2012.
"From a player's perspective, it's never nice to have a walkover to go on to the finals without a fight," said Djokovic, who also advanced to the fourth round on a walkover when German Florian Mayer pulled out of their third-round match with a groin injury.
"He has had an incredible quarter-finals match against Roger," added the Serbian, who learned the match was off just after his own morning warmup.
"Now the only thing I can think about is the final and focus on winning the title."
Nishikori said the injury troubled him in the match against Federer, but he had in fact been dealing with discomfort from it for a month -- at both Indian Wells and in the tournament at Delray Beach, Florida, before that.
When he went for his morning warm-up on Friday, he realized he just couldn't move adequately.
"I couldn't move from side to side," he said.
Nishikori said he didn't think the injury was "surgery bad" but he planned to head home to Japan as soon as possible to seek medical treatment.
It was a disappointing end to the campaign for Nishikori, who was the first Asian player since Thailand's Paradorn Srichaphan in 2003 to reach the Miami semi-finals.
"I will work with my medical team to be back healthy as soon as possible," he said in a statement on his Facebook page.