Kim Clijsters' first WTA Tour match in eight years ended in defeat to Garbine Muguruza at the Dubai Duty Free 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 seed 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 (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.
She levelled at 4-4 and saved two break points in the next game to eventually set up a tie-break, but 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.
