Stan Wawrinka lost to Alexander Bublik in the opening round of the Monte Carlo Masters on Monday as the three-time Grand Slam champion played his first ATP Tour match in 13 months.
Wawrinka, who won the Monte Carlo title in 2014, was beaten 3-6, 7-5, 6-2 by Bublik on his return from a left foot injury that forced him to undergo two surgeries last year.
The former world number three has dropped to 236 in the rankings having last played on the main tour in Qatar in March 2021.
The 37-year-old Swiss took his first tentative steps back on court at a second-tier Challenger event in Marbella last month but was defeated in the first round.