ATP Finals: Carlos Alcaraz exits after losing to Alexander Zverev

However, the 27-year-old played it down when asked if he is currently playing the best tennis of his life.

“You guys have to relax a little bit,” he said after beating the 21-year-old Alcaraz. “Three fantastic matches, now the semi-finals will be very difficult. Taylor (Fritz) has beaten me a few times at slams.

“Alcaraz has beaten me too many times this year so I’m happy to get this one. We have a great rivalry and friendship, I’m always happy to play him – unless he wins.”

Zverev continued his impressive form against Alcaraz, who has struggled with a chest complaint during this tournament and once again wore a pink nose strip to aid his breathing.

“It’s been a difficult week for me, struggling with some physical problems,” said Alcaraz, who added that he hopes to return for the Davis Cup final in Malaga next week – which will also be teammate Rafael Nadal’s last professional tournament.

“Today I faced one of the best players in the world, without a doubt, and played really solid and fantastic tennis.”

Apparently still feeling the effects of that illness, Alcaraz was again out of form but showed some fighting spirit to save seven break points in the first set, then two set points – before Zverev superbly converted the third.

Zverev saved four of those break points in the fourth game of the match, then had a point on Alcaraz’s serve as he led 6-5, but hit a forehand across the court long after a comprehensive rally. The Spaniard forced the tie-break, but Zverev was again able to get his nose in front.

After both produced excellent shots during the tie-break – including a terrific lob from Alcaraz – Zverev managed the best to finally secure the set.

His third set point saw the German dig out an attempted Alcaraz winner with a brilliant half-volley collection near the net. Alcaraz blasted the return volley wide and Zverev roared in celebration.

Zverev only needed to win the first set to guarantee his place in the last four, but he was determined to secure victory to claim the top spot in the John Newcombe Group.

The break in the second set was easier to come by as Alcaraz sent a straight volley into the net to surrender the immediate advantage.

The third seed psyched himself up enough to force two break points against Zverev at 3-2 – the first the German had faced all tournament – but was unable to convert before Zverev saw out the match.