World No.1 tennis player Novak Djokovic was in praise of Spaniard Carlos Alcaraz who upset the Serbian to set up a title clash against Germany's Alexander Zverev in the Madrid Open.

The 34-year-old Serbian was aiming to reach a record-extending 55th ATP Masters 1000 final, but was unable to overcome the 19-year-old Alcaraz, who will try and win his second Masters 1000 crown on Sunday against the world No. 3 Zverev.

Alcaraz won the three-setter 6-7(5), 7-5, 7-6(5).

"Congrats to him. He held his nerve very well," Djokovic was quoted as saying by atptour.com. "For somebody of his age to play so maturely and courageously is impressive. He deserved to win. His kick in altitude here is huge, and it was just difficult to deal with his ball, and I wasn't feeling my return from that side. He was serving a lot of kick just to put himself in a good position."

Despite the loss, Djokovic enjoyed a strong week in Madrid, earning straight-set wins against Frenchman Gael Monfils and Poland's Hubert Hurkacz as he continued to build momentum following his run to the final in Belgrade last month.

The 34-year-old, a three-time champion in Madrid, felt that his performance against Alcaraz was the best he has produced this season.

"I definitely played very good tennis, I mean, the best that I have played this year," Djokovic said. "Probably when the disappointment of losing this match passes, I will have a lot of positives to take away from this week."

Djokovic will now turn his attention to the Italian Open, which begins in Rome on Monday, where he will compete as the top seed at the final clay-court Masters 1000 of the season.