The Cincinnati Open has gotten off to a sizzling start in its first year as an extended 12-day tournament. There have been thrilling matches, including Aryna Sabalenka and Emma Raducanu's three hour battle, while Wimbledon champions Jannik Sinner and Iga Swiatek made a winning return to competition after a well-deserved break.

But it's also been a scorcher weather wise, and the players are feeling the heat. There have been four retirements and three walkovers so far, and the third round matches haven't even been completed. Arthur Rinderknech was forced to throw in the towel after collapsing mid-match against Felix Auger-Aliassime on Monday, and Auger-Aliassime has now addressed the worrying conditions in Ohio.

The No. 23 seed took the first set against Rinderknech in a tiebreak but went an early break down in set two. Auger-Aliassime levelled the score at 2-2 and was preparing to serve when his opponent fell to the ground.

Auger-Aliassime rushed over to help and medics quickly arrived. Rinderknech played on, receiving further treatment at his bench during the changeover, but retired moments later with the Canadian leading 7-6 4-2.

Now through to the last 16, Auger-Aliassime admitted the Frenchman's retirement was "sudden", but he knows the conditions have been brutal in Cincinnati, and he's also concerned about the fans.

"It feels like we're in an oven, even for the fans. We're always on the move and focused on trying to win, but the crowd is sitting for a long time, and so are our coaches," the former world No. 6 told Tennis Channel.

"A friendly reminder to everyone: drink plenty of water, bring hats, and cool off as much as possible."

Addressing Rinderknech's scare, he added: "From my point of view, it was very sudden. We spoke later, and he told me he didn't feel well today, right from the start, and it remained that way throughout the match. He tried to stay in the fight. For me, winning that first set was key."

Rinderknech isn't the only player to retire mid-match at this year's Cincinnati Open. Alejandro Davidovich Fokina had to call it quits despite leading Joao Fonseca in round two.

No. 29 seed Luciano Darderi was trailing Francisco Comesana 6-4 3-1 when he had to forfeit his opening match. And recent Canadian Open champion Ben Shelton advanced leading 6-3 3-1 when Camilo Ugo Carabelli retired.

In the women's draw, Marta Kostyuk, Leolia Jeanjean, and Camila Osorio all gave their opponents walkovers, winning at least one match each before withdrawing from the tournament.

Some players were able to finish their matches despite struggling in the searing heat. Daniil Medvedev stuck his head in a fridge on the court during his shock three-set loss to Adam Walton. And Britain's Cameron Norrie threw up after losing to Roberto Bautista Agut.

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