Jack Draper’s ATP main-draw debut at the Miami Open ended bitterly after he collapsed with a heat-related illness and was forced to retire from his first-round match against Kazakhstan’s Mikhail Kukushkin. Draper, the 2018 Wimbledon boys’ runner-up and one of the UK’s best young prospects, was granted a wildcard into the tournament due to his status as a promising client of the sports agency IMG, which runs the event. During the time he did spend on court the world No 316 handled himself well against a tricky veteran ranked more than 200 places above him, eventually losing the first set 7-5. Throughout the one-hour, 21-minute set, the 19-year-old demonstrated the potency of his powerful, left-handed game by hitting 19 winners, nearly four times as many as Kukushkin. But as the set wore on and the pair battled in a series of long deuce games, he wilted under Miami’s heat and humidity. A doctor attended to Draper with the score at 5-6, but then his legs crumpled beneath him as he reached for a backhand while facing set point. He remained on the floor for four minutes before he was helped to his feet and eventually off the court. Kukushkin, 33, has competed since 2005, when Draper was only three years old. This marks his 10th trip to Miami yet he believes he has never played in such difficult conditions. “I believe he’s a good player, young,” said Kukushkin. “It was a tough match, really tough conditions today. So hot and humid and really slow. I’ve never played in such slow conditions. The balls after one or two games started getting so big. You needed so much energy to just hit over the net. Every single game was deuce, such long rallies.” Earlier in the day, Canada’s Vasek Pospisil apologised for his outburst during Tuesday’s first-round loss to Mackenzie McDonald, in which he referred to the ATP’s chairman, Andrea Gaudenzi, as a “fucking asshole” after a contentious meeting the night before. Pospisil is one of the leading players behind the proposed breakaway Professional Tennis Players Association. “An hour [and a] half yesterday, chair of the ATP fucking screaming at me in a player meeting for trying to unite the players,” said Pospisil during his match. “For an hour and a half. The leader of the ATP. Get him out here. Fucking asshole.”