Ronnie O'Sullivan took a series of 'power naps' during his last 16 victory over Li Hang at the Scottish Open in Glasgow.
The five-time world champion was seen slumped in his chair during a tight 4-3 win over China's Hang and revealed afterwards his snoozes were taken on the advice of his doctor.
O'Sullivan told Eurosport: "My doctor's told me to catch some rest whenever I can because he knows I've had a busy eight weeks.
"So even when I thought I shouldn't be sleeping, I've just been sleeping and it's working.
"It's just a little snooze -- everyone needs a snooze."
On December 10, O'Sullivan clinched a record-equalling sixth UK Championship - drawing level with Steve Davis' success at the tournament and also matching Stephen Hendry's all-time haul of 18 major titles.