The 24-time grand slam champion had not played in China since 2019 but chose it as the venue for his first ATP Tour event since May.

Djokovic plays sparingly these days and had contested only a Davis Cup match for Serbia since a shock loss to Alexei Popyrin in the third round of the US Open in August.

American Michelsen took advantage of a slow start from Djokovic before fighting back in the second set but the 37-year-old was the stronger when it mattered to claim a 7-6(3) 7-6(9) victory.

It was a first meeting for the pair, and Djokovic said of his big-hitting 20-year-old opponent: "I've watched him play but never faced him on the court.

"I also haven't played in a while so it took me a bit of time to get the rust off and get things going but he started off terrifically, big serves and a quite aggressive style of tennis.

"For a big guy he moves well, comes in, he's not afraid to step it up and take it to his opponent. It was a very close encounter, I thought it was quite a high level of tennis. I'm just glad to keep my calm when it mattered in the second set tie-break."

Michelsen, ranked 43, surged into a 3-0 lead but back came Djokovic to level at 4-4, and the fourth seed dominated the tie-break.

Djokovic looked in total control at 4-1 up in the second set only for Michelsen to mount a comeback, and the American had two chances in the tie-break to force a deciding set but could not take either.

Carlos Alcaraz and Jannik Sinner both shrugged off the quick turnaround from their epic final in Beijing on Wednesday with comfortable victories.

Alcaraz defeated China's Shang Juncheng 6-2 6-2 while Sinner beat Taro Daniel 6-1 6-4 but sixth seed Andrey Rublev lost in three sets to teenage Czech Jakub Mensik.

READ MORE: Coco Gauff dominates Karolina Muchova to win China Open

EDEN-HAZARD

Belgium's Eden Hazard announces international retirement

Belgium's 'Golden Generation' past best, says Hazard

Editors Pick