Carlos Alcaraz sealed his place in the Madrid Masters semi-finals on Wednesday after a sensational second-set comeback against Karen Khachanov.
The world No 2 took the first set 6-4 but then found himself 5-2 down in the second before fighting back to win 7-5 at Manolo Santana Stadium.
It means Alcaraz, who thrashed Alexander Zverev in the previous round, keeps his title defence firmly on track as he reached his third ATP Masters 1000 semi-final of the season.
The 19-year-old top seed is now two wins away from claiming his fourth straight ATP Tour title on home soil and will play either Germany's Borna Coric or Daniel Altmaier of Croatia in the last four.
If Alcaraz retains his crown in the Spanish capital he will remain firmly on course to leapfrog Novak Djokovic at the top of the world rankings, which he will do simply by playing a match at the Rome Masters later this month.
“Winning this match will give me a lot of confidence, Karen was at a great level and took me to the limit,” said Alcaraz, who unleashed 31 winners against the 10th seed.
“It was decided by small details and I am very, very happy to be able to get through this round.”
The Russian, who knocked out countryman and fifth seed Andrey Rublev this week, showed no fear in the first set despite his opponent's form.
Eventually, Alcaraz found a decisive break to take a 4-3 lead with a strong forehand that Khachanov could not return successfully. The Spaniard consolidated and served it out.
In the second set, Khachanov broke for a 3-1 lead when Alcaraz went long after saving a first break point.
The world No 12 forced two more in the sixth game but could not convert either as Alcaraz fought hard to hold.
Alcaraz's perseverance paid off as he broke with a volley to get back on serve at 4-5.
The US Open champion consolidated his break and then earned another when Khachanov hit the net with an attempted forehand winner.
Aiming for his 10th tour level title the crowd-pleasing home favourite sealed his progress with a powerful forehand drive.
In the women's draw, third seed Jessica Pegula was knocked out 6-4, 0-6, 6-4 by Veronika Kudermetova as the Russian reached the semi-finals of a WTA 1000 event for the first time.
The American was trying to reach her second consecutive final in Madrid, after losing to Ons Jabeur at the clay-court tournament last year.
“I feel so happy and proud of myself, because every match I played three sets,” said Kudermetova, who will face either world No 1 Iga Swiatek or Petra Martic in the last four. “Before this match, every match was almost three hours. Today, only two hours, I feel fresh.”
