Novak Djokovic had to come from behind to beat Kei Nishikori and keep his bid for a calendar Grand Slam alive as he advanced to the US Open fourth round on Saturday.

The world number one overcame a loose first set to win 6-7, 6-3, 6-3, 6-2 and beat the Japanese for the 17th time in a row. The Serb, 34, is aiming for a men’s record 21st Grand Slam title.

He will face American Jenson Brooksby next after the wildcard beat Russian 21st seed Aslan Karatsev in five sets. Brooksby, the world number 99, came from behind to win 6-2, 3-6, 2-6, 6-3, 6-3 and become the youngest man from the USA to reach the US Open fourth round since Andy Roddick in 2002.

German qualifier Oscar Otte reached the fourth round of a Grand Slam for the first time with victory over Italy’s Andrea Seppi. World number 114 Otte, who was match point down in his first two qualifying matches, won 6-3, 6-4, 2-6, 7-5. 

Otte will face Wimbledon finalist Matteo Berrettini, who had to work hard to see off Belarusian Ilya Ivashka. The Italian sixth seed hit 69 winners as he came through 6-7 (5-7) 6-2 6-4 2-6 6-3.

Italian 13th seed Jannik Sinner overcame Gael Monfils in five sets, weathering a fightback from the Frenchman to win 7-6, 6-2, 4-6, 4-6, 6-4. Sinner will meet German fourth seed Alexander Zverev who advanced after opponent Jack Sock retired with a thigh injury trailing 3-6, 6-2, 6-3, 2-1.

BBC