Thanasi Kokkinakis has withdrawn from the Adelaide International with a shoulder injury, putting his participation in the Australian Open in major doubt.
Luckless Kokkinakis was set to face Valentin Vacherot in the second round, with the Monaco player now advancing straight through to the quarter-finals.
The 29-year-old South Australian made his highly anticipated return to singles action on Monday evening after nearly 12 months away following pectoral surgery last February.
He battled past American Sebastian Korda to win a final-set tiebreak, but struggled with his right shoulder.
After the match Kokkinakis predicted his shoulder would require anti-inflammatories and physiotherapy.
He conceded that if it wasn't his home tournament, he probably wouldn't have played the first-round match.
Kokkinakis said it was a different pain to the pectoral problems that had long plagued him, undergoing revolutionary surgery last year to have a dead person's achilles tendon surgically knotted between his right pectoral muscle and shoulder.
He has a protected ranking to enter the singles at Melbourne Park, where he's also scheduled to play doubles with fellow Australian and good mate Nick Kyrgios.
