His face was creased with worry as he trailed a pumped-up rival, but Rafael Nadal re-emerged after an overnight rain delay to blow away Diego Schwartzman at Roland Garros.
The 10-time champion lost the first set 6-4 to the impressive Argentine Wednesday, but returned under sunny skies Thursday to win the next three sets 6-3 6-2 6-2 to reach the French Open semifinals.
Rafael Nadal fights back to beat Diego Schwartzman in four sets
10-time champion reaches semifinal
Nadal wins 4-6 6-3 6-2 6-2
Spain's Nadal will next play another Argentine Juan Martin del Potro after the former US Open champion beat Marin Cilic 7-6 5-7 6-3 7-5.
Nadal, dubbed the "King of Clay" for his domination on the red dirt, had his back against the wall at 3-2 down in the second set Wednesday before the match was halted for rain.
"I felt that I was playing a little bit under more stress than usual, and he was able to take control of the point too many times," said Nadal.
The delay enabled Nadal to regroup and he turned the deficit into a 5-3 lead before a second stoppage ended play for the day.
Returning to Court Philippe Chatrier Thursday, Nadal quickly polished off the second set, and with it, effectively, Schwartzman's challenge.
Despite some spirited resistance, the 11th seed couldn't live with Nadal's new-found intensity and revamped strategy, and the 16-time grand slam champion sealed the victory for the loss of only four games with his fourth match point.
"I played more aggressive. I continued the level of intensity that I played after the first stop. And in my opinion, the match changed," Nadal said.
He added: "It was a very difficult match against a good friend and good player. For me it's always big emotions to win here."
Nadal's streak of 37 consecutive set wins at Roland Garros ended Wednesday, but with victory the 32-year-old became only the third player in the Open era (since 1968) to reach 11 semifinals in the same grand slam. Roger Federer (Wimbledon) and Jimmy Connors (US Open) are the others.
No player in history has won as many grand slam titles at a single tournament as Nadal has in Paris.
Nadal won the French Open on his debut as a 19-year-old and came into this year's event with a 79-2 win-loss record at Roland Garros.