Carlos Alcaraz reaches Madrid Masters last four but made to fight by Karen Khachanov

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.

Incredible performance