In the women's last-eight, Maria Sharapova faces fellow former Paris champion Garbine Muguruza. No. 10 Sloane Stephens beat No. 13 Madison Keys 6-4, 6-4.
Rain still starring in the French Open! "[Del Potro plays an] aggressive game from the end of the court, the baseline".
But Thiem, unusually standing up to Nadal's first serve, forced two break points in the next game and converted the second with a flashing forehand into the right corner.
After dropping the opening set of his first round match he won the next 12.
He was serving in the fourth game when he went back to his chair and unwrapped strapping on his left wrist.
Spanish world number 1, Rafael Nadal fended off a tough challenge from Diego Schwartzman to enter the French Open semifinals.
The Austrian was more emphatic in the third set, powering his way to a 6-1 win behind a strong serve.
Nadal is now 85-2 for his career at Roland Garros, with a record 10 championships.
Nadal will advance to play Juan Martin del Potro, who defeated Marin Cilic in four sets after play was suspended Wednesday at 6-6 in the first set.
The 37-set run was Nadal's longest at the French Open.
"At the beginning yesterday there were no options to open the court, to win points", Nadal explained. Upon resumption on Thursday, the defending champion stepped on the gas and crushed Schwartzman 4-6, 6-3, 6-2, 6-2.
"Today‚ all day‚ on Philippe Chatrier‚ the fans said "Forza‚ Marco"‚ so I think this is the best moment for me‚" said Cecchinato.
"He was playing great, and I was playing too defensive".
Both players also held their nerve early on during the semi-final stage.
He put out seeded players Pablo Carreno Busta and David Goffin before the seismic shock of knocking out 2016 champion Djokovic in the quarter-finals.
She twice has lost in the final at Roland Garros - to Maria Sharapova in 2014 and to Jelena Ostapenko in 2017 - and was the runner-up to Caroline Wozniacki at the Australian Open in January.
The German left-hander had lost in the first round in the last two years.
"There is a reason why he won 11 times here", said Thiem, a 24-year-old Austrian appearing in his first major final. If last year it was Roy Emerson to reward Rafael Nadal for the tenth Spanish title in Paris, this year, for the 2018 edition, they chose Ken Rosewall, 50 years after his second victory in the Parisian Slam! He stormed through the next five games to take the set and move back into the lead.
"True, I understand that everybody here, you have to write things", he said.
A hold to love showed Thiem had not given up the ghost, however unlikely a repeat of Simona Halep's heroics from the same position a day earlier seemed.
Nadal can become just the second male player in the Open era to reach 11 finals at the same Grand Slam tournament, equaling Roger Federer's record at Wimbledon. "I was always wanting to win", Schwartzman said.
Next up for Thiem is either Nadal, who is eyeing his 11th French Open title, or Juan Martin del Potro of Argentina.
Thiem is contesting his first Grand Slam final.
Kerber, a former USA and Australian Ooen champion and ex-number one is in her second quarter-final in Paris, six years after her first.