The British world number 30 appeared to be struggling with the conditions as temperatures soared to 30 C, forcing tournament organisers to apply the heat rule in the first two days of competition.

Raducanu broke in the opening game of the match but immediately lost her advantage and would not win another game in a 28-minute first set.

The 2021 US Open champion received medical attention five games into the second set.

She made the call to retire, sending Li into a second-round meeting with ninth-seeded Ekaterina Alexandrova.

The heat rule allows players to take a 10-minute break between the second and third sets, and means the tournament can partially or fully close the roof to protect players from the heat.

In the Raducanu-Li match the roof was partially closed.

Earlier, four-time major champion Naomi Osaka claimed her first-ever victory at the Wuhan Open with a hard-fought 4-6, 7-5, 6-3 victory over Canada's Leylah Fernandez.

In a tense two-hour 30-minute affair, the 11th-seeded Osaka fired 41 winners and 56 unforced errors.

Osaka, who is playing in Wuhan for the first time since 2017, awaits in-form Linda Noskova or Kazakhstan’s Yulia Putintseva in the second round.

"Mentally it was just really tough for me today," said Osaka. "And I think it's a part of the season that's just tough. But I think I'm, like, really happy to have gotten through it, and I think it'll be easier from now on."