Djokovic is looking to become the first man to win the ‘Golden Slam’ which would involve the Serb winning Olympic gold and all four Grand Slams in the same year.
The 20-time Grand Salm champion has already won the Australian Open, Roland Garros and Wimbledon this year with victories in Tokyo and the US Open later in the summer needed to secure the historic achievement.
And his chances of winning a first gold medal at the Olympics have been boosted by results on day two.
No 5 seed Andrey Rublev was a potential quarter-final opponent for the Serb but crashed out at the hands of home favourite Kei Nishikori.
The Russian lost 6-3, 6-4 to the former US Open finalist in just over an hour.
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A statement from Murray said: “I am really disappointed at having to withdraw but the medical staff have advised me against playing in both events.
“I have made the difficult decision to withdraw from the singles and focus on playing doubles with Joe.”
Murray’s scheduled first round opponent was then beaten by Australian Max Purcell in a shock straight sets loss.
Auger Aliassime was heavily fancied to beat the Aussie after Murray’s withdrawal and to make a deep run in the men’s singles.
The Canadian is fresh from reaching the quarter-finals of Wimbledon – his best performance at a Grand Slam.
But the 20-year old’s exit will be just more good news for the Serb.
Still in the draw though are the No 2 and 3 seeds Daniil Medvedev and Stefanos Tsitsipas who both won their opening matches.
The Russian beat Alexander Bublik in straight sets whilst Tsitsipas had to battle through a three set tussle against Philipp Kohlschreiber.
Djokovic will be pleasing though that they both sit on the opposite side of the draw so can not play the world No 1 until the final.