Harry Styles "couldn't handle the heat" at a Bikram yoga class.
The 19-year-old One Direction star practiced the popular form of yoga, which usually includes a series of 26 postures and two breathing excercises in a room heated to about 40 degrees Celsius, while in Australia but found the classes tough, much to the amusement of his female classmates.
A source told The Sun newspaper: "Harry couldn't handle the heat.
"The class lasts 90 minutes and is pretty intense but the girls in the class were ribbing him for having to sit down during the exercises.
"He took all the winding up in good spirits and said afterwards it was the 'toughest session' he'd ever experienced.
"The girls thought he was a real gent."
1D's personal trainers introduced Harry to it as part of his bid to tone up.
The star also works out in the middle of the night because he's so lonely and is exhausted as One Direction - which includes Louis Tomlinson, Zayn Malik, Niall Horan and Liam Payne - come to the final dates of their Take Me Home world tour which kicked off in London in February.
A source previously said: "He suffers from terrible homesickness and exhaustion towards the end of a tour. He often wakes his personal trainer Mark in the middle of the night because he's so lonely that he'd prefer them to work out together than be on his own."
1D are set to take the to the stage at Sydney's Allphones Arena for the next three nights before they finish off the Australian leg of their tour in the country's culture capital Melbourne, where they will perform at Rod Laver Arena between October 28-30.