Maria Sharapova cut her Russian return short.
Sharapova withdrew from St. Petersburg citing a right shoulder injury prior to her scheduled second-round match vs. compatriot Daria Kasatkina.
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"I tried to do everything possible to be able to be ready to compete this week, but my right shoulder continues to be an issue for me," Sharapova said. "I will meet with my team of doctors over the next few days to evaluate the situation, and I look forward to returning to completion as soon as possible."
The walkover sends the third-seeded Kasatkina into a quarterfinal against either fifth-seeded Julia Goerges or Russian wild card Vera Zvonareva.
Meanwhile, Sharapova's injury issues continue.
The 31-year-old Russian has played three tournaments this year and failed to finish two of them.
Sharapova also retired from the Shenzhen quarterfinals while trailing eventual-champion Aryna Sabalenka, 6-1, 4-2.
The five-time Grand Slam champion contested just 11 tournaments in 2018.
Sharapova closed the curtain on the 2018 season following a straight-sets loss to Carla Suárez Navarro at the US Open.
Despite more than three months of rest and recovery, the 29th-ranked Russian opened the season in Shenzhen wearing taping around her surgically-repaired right shoulder prompting speculation she is hurting.
Since returning to the pro circuit from a 15-month doping suspension in 2017, Sharapova has contested just 22 tournaments and won only one title, defeating Sabalenka in the 2017 Tianjin final.
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