BEAVERTON, United States — Nike became a target of jokes when a star US college basketball player sprained a knee mid-game because one of his shoes split during play.

Duke University star Zion Williamson limped off the court after the mishap during the game against his school’s arch rival University of North Carolina. Twitter lit up with jibes and jeers aimed at the No. 1 sports brand, pushing the keyword Zion to the top of the worldwide trending list as of Wednesday night; Duke followed and Nike came fourth.

Former President Barack Obama, courtside at the high-profile clash, was shown on video appearing to say with an incredulous look: “His shoe broke!”

“We are obviously concerned and want to wish Zion a speedy recovery,” Nike said by email. “While this is an isolated occurrence, we are working to identify the issue.”

Williamson suffered a mild knee sprain, according to Duke’s coach Mike Krzyzewski. UNC defeated Duke 88-72 after Williamson exited less than one minute into the game, handing AP’s top nationally ranked team its third loss this season.

This isn’t the first time that Nike’s had problems with its basketball merchandise. After taking over as the official NBA uniform supplier in 2017, multiple stars including LeBron James had their jerseys rip.

Nike shares fell as much as 1.4 percent to $83.65 in premarket trading. The stock is up 27 percent in the past year, similar to the 28 percent rise of Puma and leading the 12 percent gain of Adidas.

Puma is an upstart in the basketball market, and one of its few NBA players, Terry Rozier of the Boston Celtics, took advantage of Nike’s stumble to urge others to join him.

By Michael Sin with assistance from Tim Loh; editors: Niluksi Koswanage, John Edwards III and John Lauerman.