Stan Wawrinka opened his 2020 season with a straight-sets win over Frenchman Jeremy Chardy on Tuesday to reach the quarter-finals of the ATP event in Doha.
The three-time Grand Slam champion, the top seed in Qatar, eased to a 6-3, 6-4 victory to set up a last-eight tie against Slovenia's Aljaz Bedene.
The 34-year-old battled back from a break down in the second set to win in under an hour and a half.
The Swiss star was 66th in the ATP rankings 12 months ago after struggling with knee injuries, but a solid 2019 campaign has seen him rise to world number 15.
"I'm happy to still be playing at a good level," he told atptour.com after winning his first competitive match since a last-16 loss to Rafael Nadal at the Paris Masters last October.
"I'm happy to be here for another year and hopefully (it will be) a good one for me."
Wawrinka is playing the tournament for only the second time since a 2008 final defeat by Andy Murray, having lost to Roberto Bautista Agut in last year's quarter-finals.