Alexander Zverev squandered a big opportunity to close the gap to Jannik Sinner at the top of the ATP Rankings after his shock exit at the Rio Open.

The German lost 6-4, 3-6, 4-6 to world No 86 Francisco Comesana in the quarter-finals of the clay-court ATP 500 tournament.

The three-time Grand Slam runner-up led 4-1 in the third set, but his 24-year-old Argentine opponent won five straight games from that position to seal a sizeable upset.

Following his defeat to Comesana, Zverev said: “Better level than Buenos Aires, but unfortunate to finish the tournament like this.

“I still enjoyed my time in Rio and hope to come back. It’s one of the most beautiful 500s that I’ve ever played. Shame because I was in a winning position.”

Zverev, the world No 2, was the only top 25 player in the draw in Rio following the withdrawals of Holger Rune and Lorenzo Musetti.

Sebastian Baez, the defending champion and world No 31, is the only top 50 player in the semi-final lineup.

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Speaking earlier in the tournament, Zverev did not hide from the fact that becoming world No 1 for the first time is one of his key objectives.

“I’m not number one in the world yet, but I want to be,” the 27-year-old said. “My goal is to fight for the big titles and the top spot in the rankings with Alcaraz and Sinner. There are things they do better than me. I have to improve.”

With world No 1 Sinner banned from playing on the ATP Tour until May 4 due to failed doping tests, both Zverev and Carlos Alcaraz have a chance to make up ground.

Zverev will remain on the 8,135 points he started the week with after his quarter-final exit in Rio, which leaves him 3,195 points adrift of Sinner. He could have collected a further 400 points had he won the 500 event.

Alcaraz also missed an opportunity this week as he fell in the quarter-finals of the Qatar Open — leaving him with 7,510 points in the live rankings.

Sinner will drop 1,600 while he is on the sidelines, which will put him on 9,730 points when he makes his comeback at the Italian Open in May.

During this period, Zverev is defending 850 points, while Alcaraz will defend 1,400.

The German, therefore, needs to earn 2,446 points, while Alcaraz will require 3,721 points, to overtake Sinner by the time the Rome ATP Masters 1000 event begins.

Zverev will next compete at the Mexican Open, an ATP 500 tournament in Acapulco which begins next week.

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