Nick Kyrgios won't be launching clay-court season in Houston.

Kyrgios and Yoshihito Nishioka withdrew from next month’s Fayez Sarofim & Co. U.S. Men’s Clay Court Championship set for April 6-14th at River Oaks Country Club.

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Kyrgios has a patella tendon issue that will prevent him from playing at River Oaks.

“I am really disappointed to have to pull out of Houston this year,” Kyrgios said. "I loved playing the event last year and was looking forward to returning but unfortunately my knee has other ideas.

"I need to rest up, get treatment and make sure I can actually play on the European clay this year after I missed the whole swing in 2018. I know the Houston ATP 250 will be great again this year and I plan on returning in 2020.”

Nishioka has an ongoing back injury that has sidelined him for a few weeks.

"I am really sorry to have to withdraw from Houston," he said. "I hurt my back in Indian Wells and unfortunately it is not ready enough to compete in Houston this year. I look forward to playing there in 2020."

The spots in the draw will be take by former U.S. Clay quarterfinalist Paolo Lorenzi and 20-year-old Casper Ruud, who’s father Christian won the 1996 River Oaks International. 

Photo credit: Mark Peterson/Corleve