Defending champion Yuan Yue of China suffered an early exit at the WTA 250 ATX Open in Austin on Monday.

Fourth seed Yuan, who triumphed at last year's tournament with a straight-sets win over compatriot Wang Xiyu, fell to Australia's Kimberly Birrell 6-7(5), 6-7(5) in a grueling first-round match that lasted two hours and 12 minutes.

Yuan's early exit contrasts sharply with her breakthrough performance here last March, when she captured her maiden WTA title.