World number one Djokovic can complete the Golden Slam by adding a maiden gold medal to a sweep of the four majors he achieved at the French Open in June.

Defending champions Murray and Serena Williams, the injury-hit Rafael Nadal and Venus Williams are all in a position to become the first players to win more than one singles gold since tennis returned to the Games in 1988.

Top seed Djokovic appears to have the toughest task when he faces Juan Martin del Potro in his opener on Saturday. The Serb was defeated by the giant Argentine in straight sets in the bronze medal match four years ago.

Djokovic has an 11-3 record against Del Potro, although the two have not met for three years.

Del Potro, the 2009 US Open champion, comes into Rio with a world ranking of 145 having been as high as four in 2011 before his career was almost ended by four wrist operations.

"This match is going to be completely different. My game is not as good as I played four years ago," said Del Potro.

Djokovic said he never had any intention of pulling out of Rio where five of the world's top 10 :  Roger Federer, Stan Wawrinka, Milos Raonic, Tomas Berdych and Dominic Thiem will be missing.

"It's my number one goal. It would mean the world to me to crown my career with gold, it would rank as one of my highest achievements," said Djokovic.

Murray, too, always intended to play even though he has not set foot on a tennis court competitively since winning a second Wimbledon in July. Grand Slam breakthrough
   
His Olympics victory in 2012 set the foundation for his eventual Grand Slam breakthrough. After downing Federer for gold, he went on to become the first British man to win a Grand Slam singles title in 76 years when he triumphed at the US Open.

The 29-year-old has backed that up with the 2013 and 2016 Wimbledon titles. "It was great winning Wimbledon but time to move on now and focus on this event and the next few months," said the Scot.

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