Heat exhaustion ruined Iva Jokic’s teenage dream of a third-round meeting with Aryna Sabalenka at the US Open.

American Jokic, who is 16 and the youngest player in the main draw, was a set up against 29th seed Ekaterina Alexandrova.

But in sweltering conditions, where the mercury was nearly 40C, the heat got the better of her midway through the second set.

She needed medical treatment and had her blood pressure and pulse checked.

Jokic, a semi-finalist in the Wimbledon juniors last month, rejoined the match but Alexandrova took the second set.

To her credit, Jokic came back to life and was agonisingly close to another famous victory in a topsy-turvy final-set decider.

She staved off six match points as a tiebreak was on the cards before the Russian eventually claimed a 4-6 6-4 7-5 victory.

Sabalenka is waiting in the third round after last year’s finalist coasted past Lucia Bronzetti 6-3 6-1.

There was a nice moment as she met with a young fan dressed like her, including a replica tiger tattoo after the match.

The Belarussian said: “It was really adorable moment. I just looked up, and I saw on the big screen a mini-me. It was so cute.

“It’s such a motivation to keep going to inspire the young generation. That’s the main goal.”

The openness and fragility of the women’s top seeds were again highlighted as Wimbledon champion Barbora Krejcikova was ousted in the second round.

The Czech, who beat Jasmine Paolini in the final at SW19 last month, crashed out to world number 61 Elena-Gabriela Ruse.

Olympic champion Zheng Qinwen came from a set down to beat Erika Andreeva 6-7 (3) 6-1 6-2.