Defending champion Lilia Vu withdrew from the Chevron Championship moments before her first-round tee time Thursday afternoon due to a back injury.

According to the LPGA, Vu withdrew after her pre-round warmups. Vu had been battling the injury earlier this season and said before the first major of the season that her body felt “95 percent there.”

Ranked No. 2 in the world, Vu was slated to tee off with World No. 1 Nelly Korda and Australian Minjee Lee at 1:10 p.m. local time at The Club at Carlton Woods near Houston.

Vu won four times on tour last season, including two majors. After beating Angel Yin in a playoff at the Chevron, she cruised to a six-stroke win at the AIG Women’s Open. She won LPGA Tour Player of the Year honors.