Novak Djokovic continued his bid to hold all four Grand Slam titles. © AFP Novak Djokovic on Monday became the first man to reach the French Open quarter-finals for 10 successive seasons while Kei Nishikori set-up the toughest challenge on a clay court — facing Rafael Nadal. Top seed and world number one Djokovic continued his bid to hold all four Grand Slam titles simultaneously for the second time by thrashing Germany’s Jan-Lennard Struff 6-3, 6-2, 6-2. The 32-year-old will now face either ninth-seeded Italian Fabio Fognini or fifth seed Alexander Zverev in what will be his 13th appearance overall in the quarter-finals in Paris.”It was tricky with the rain, but that’s Paris,” said the 2016 champion after playing in drizzly conditions.”I’m really confident with my serve. I hope it continues like that.”German fifth seed Zverev reached his second successive Roland Garros quarter-final with a 3-6, 6-2, 6-2, 7-6 (7/5) win over Italy’s Fabio Fognini.Last year he achieved his best run at the Slams, making the quarter-finals where he was defeated by eventual runner-up Dominic Thiem.’Tough against Novak’ ”It’s going to a great match and a tough battle against Novak, the world number one, it’s going to be interesting,” said Zverev…