Novak Djokovic remains on course for a 'Golden Slam' after ruthlessly ending the dreams of home hope Kei Nishikori to cruise into the Olympic semi-finals.

The world number one, bidding to become the first man to win all four Grand Slam titles and an Olympic gold in the same year, breezed through 6-2 6-0.

He will face Germany's Alexander Zverev in the semi-finals on Friday.

Switzerland's Belinda Bencic and the Czech Republic's Marketa Vondrousova will meet in Saturday's women's final.

Bencic outlasted Kazakhstan's Elena Rybakina 7-6 (7-2) 4-6 6-3 in a match lasting almost three hours in the searing Tokyo heat, saving five set points in a 73-minute opening set that she won on a tie-break.

The Swiss later returned to the court to become the fifth player to reach finals in both singles and doubles at a Games since tennis was reintroduced to the Olympics in 1988, as she and Viktorija Golubic beat Brazilian pair Laura Pigossi and Luisa Stefani 7-5 6-3.

Vondrousova, ranked 42nd in the world, enjoyed a far more serene passage as she followed up her upset of Naomi Osaka by shocking world number six Elina Svitolina 6-3 6-1 in little over an hour.