Former world No.1 Kim Clijsters' first WTA Tour match in eight years has ended in defeat to Garbine Muguruza at the Dubai Tennis Championships.
At 36, the Belgian is 10 years Muguruza's senior as well as a mother of three, but her last match action came at the 2012 US Open.
It was her second retirement, having spent two years out of the game from 2007 - aged 23 - to 2009.
Drawn against the ninth seeded Spaniard and this year's Australian Open runner-up on her return, Clijsters battled well after an understandably slow start but was beaten 6-2 7-6 (8-6) in an hour and 37 minutes.
Clijsters served five double faults as she lost a 32-minute first set and when she went a break down in the second, it looked like being a short-lived first outing on her latest comeback.
But she levelled at 4-4 and saved two break points in the next game to eventually set up a tie-break.
However, the Spaniard had too much in the tank and took it 8-6 to advance to a last-16 clash with either Veronika Kudermetova or Dayana Yastremska.
Australian Open quarter-finalist Ons Jabeur continued her great form from Melbourne to Dubai, where she upset world No.18 Alison Riske to reach the second round.
The Tunisian, who is the highest-ranked Arab woman in history, and is the first Arab woman to make a grand slam quarter-final since 2004, overcame foot blisters to squeak past Riske 7-6 (7-3) 1-6 6-3 and set up a last-16 clash with top-seeded Romanian Simona Halep.
It was Riske's first defeat to a player ranked outside the top five this season.
Earlier on Centre Court, 2016 finalist Barbora Strycova survived a wild opening round against American teen Amanda Anisimova, recovering from a 1-3 deficit in the decider to advance 7-6 (7-3) 2-6 6-4.
The WTA debuted a new rule, allowing coaches to give their players hand signals and brief instructions from the stands, on a trial basis.
Jabeur, who parted ways with Frenchman Bertrand Perret after the Australian Open and is now working with two coaches Issam Jellali and Othmane Garma, is pleased with this new development but joked that some words from her mentors can aggravate her while playing.
"Issam was talking. Before the match I told him, 'Do not use some words because sometimes they drive me crazy. Think twice before saying anything on the court'," she said with a laugh.
"Before, I found it really weird to get a code violation or something for coaching. Everyone was talking."
Australian Associated Press