Murray helped Great Britain reach the Davis Cup quarter-finals last week
Andy Murray lost to Aslan Karatsev in the last 16 of the Zhuhai Championships in China.
The Russian, who reached the 2021 Australian Open semi-finals as a qualifier, came through 4-6 6-3 6-2.
Murray led 5-2 in the opening set and held off a Karasev fightback to take it but the world number 63 was the stronger after that.
The veteran Scot lost his serve twice in the second and third sets as Karatsev wrapped up the victory.
It made it two wins out of two for Karatsev, who had also beaten Murray in their only previous career meeting in the 2022 Sydney Classic final.
Karatsev will face another Briton in the last eight after Cameron Norrie swept past Australian qualifier Marc Polmans 6-0 6-3.
The world number 17 won 90% (26/29) of his first-serve points and did not face a break point on his way to victory as he chases his second title of the season.