Lyon, France, 23 May 2017 | AAP

Thanasi Kokkinakis’ long-awaited return to the ATP Tour didn’t exactly go to plan with the 21-year-old Australian falling to Uzbek world No.81 Denis Istomin 6-3 6-4 in the first round in Lyon.

Kokkinakis, who has spent the last 18 months battling debilitating injuries to his shoulder and abdomen, delivered a serviceable performance but it appeared he was well below his best.

His forehand, usually a strength, was at times erratic and he failed to make any inroads on Istomin’s serve.

The Uzbek never faced a break point throughout the match and broke Kokkinakis in the first game of both sets to make the second round in comfortable fashion.

There he will face tournament top seed Milos Raonic.

It was Kokkinakis’ first ATP Tour main draw singles match since he suffered a three-set loss to Frenchman Jeremy Chardy in October 2015 at the Stockholm Open.

Joining Istomin in the second round were young South Korean star Hyeon Chung, who thrashed Donald Young 6-2 6-3, and Argentine qualifier Nicolas Kicker, who beat Germany’s Dustin Brown 6-4 6-4 to book a second-round showdown with Nick Kyrgios.