TOKYO -- World No 1 Novak Djokovic from Serbia was unable to achieve a "Golden Slam" after losing to Germany's Alexander Zverev in the men's singles semifinals at the Tokyo Olympics here on Friday.

Djokovic, seeking to become the first man to win all four majors and an Olympic gold medal in a season, fell to world No. 5 Zverev 1-6, 6-3, 6-1 after two hours and three minutes.

Zverev registered 71 percent on his first serves and converted 3 of 5 break points, while the Serbian failed on all four attempts. Djokovic had seven unforced errors, compared with his German opponent's three.

Djokovic has captured the Australian Open, French Open and Wimbledon titles this year.

Zverev will vie for the Olympic gold medal with Russian Olympic Committee (ROC) player Karen Khachanov, who saw off Pablo Carreno Busta of Spain 6-3, 6-3.