Wimbledon was, officially, as scorching as anywhere else in the United Kingdom on Monday.

But the world’s premier tennis players nonetheless faced off on the venue’s famous grass courts as temperatures soared past 90 degrees Fahrenheit, or more than 32 degrees Celsius, making it the hottest opening day for the tournament since it began 148 years ago.

The sun beat down on everyone — players, referees, fans, ball boys and girls. Even for a competition that is regularly played in the summer, the weather tested the fortitude of just about everyone gathered at the All England Lawn Tennis and Croquet Club about a half-hour outside central London.

Organizers of the storied event had put in place special measures to combat the heat: There were more than 100 water refill stations dotted around the grounds for spectators and staff, more than ever. The club distributed 6,700 refillable water bottles to its staff. Special shade areas were set up.

“We are prepared for the predicted hot weather, with comprehensive plans in place,” the tournament organizers said in a statement as the games began. “Shade mapping (a detailed shade study) helps our stewards guide guests to the coolest areas.”

In spite of this, for some spectators it was too much.

During his first-round match on Centre Court, Carlos Alcaraz, the Spanish player and defending Wimbledon champion, was one of the first to notice when a fan in the stands collapsed. He pointed out the incident to the officials and handed a cold water bottle into the crowd. The fifth set was delayed for about 16 minutes while medical personnel attended to the spectator.