Matt Ebden's luck has run out at the Paris Masters with the Australian forced to bow out of the final ATP Masters 1000 event of the year through injury.
Ebden, who lost in the final round of qualifying, had been given a reprieve when he replaced Kyle Edmund in the main draw after the Briton withdraw due to a knee injury.
But the 30-year-old Ebden was forced to retire 45 minutes into his match with Karen Khachanov on Tuesday.
After losing the first set 6-2 and struggling with his serve, Ebden pulled the pin down 2-0 in the second set.
Novak Djokovic began his campaign to reclaim the world No.1 ranking with a 7-5 6-1 victory over Joao Sousa.
The 31-year-old Serb can take the top spot in the rankings from Rafael Nadal if he wins a record extending fifth title in the French capital.
After a tough first set Djokovic rolled through the second set despite fighting through a flu-like illness to win in one hour and 33 minutes.
"I don't want to get into details but I think it's a minor thing," he said.
The 2018 Wimbledon and US Open champion is on a stellar run having lost only twice in 34 matches and has also won the past two Masters crowns in Shanghai and Cincinnati.
Djokovic will face Damir Dzumhur next after the Bosnian advanced with a 6-3 6-3 win over Greek 14th seed Stefanos Tsitsipas.
World No.7 Marin Cilic is through to round three with a 6-3 6-4 triumph over Philipp Kohlschreiber.
Milos Raonic battled past local favourite Jo-Wilfried Tsonga to win 6-7 (4-7) 7-6 (7-5) 7-6 (7-5) to earn a tie with Roger Federer.
"I feel like it's better for me to play matches rather than practice," Federer said in the lead-up to the ATP Finals starting on November 11.
"As long as I don't feel like I'm taking a chance on my health prior to London, that's the key as well."
Others to progress to the second round in Paris were Gilles Simon, Marton Fucsovics, Mikhail Kukushkin, Daniil Medvedev and Fernando Verdasco - who will play compatriot Nadal.
