Japan's Kei Nishikori lost his opening match of the clay season Wednesday, with Asia's top player crashing to a 7-5, 6-4 defeat to Pierre-Hugues Herbert at the Monte Carlo Masters. Fifth seed Nishikori reached the final here last year but will lose a chunk of ranking points after he hit 25 unforced errors and just 14 winners in succumbing to Frenchman Herbert. Nishikori will now move on to Barcelona next week, where he owns two titles as he works on his clay form as the run-up to Roland Garros intensifies. Herbert, who overcame Fernando Verdasco in the first roud, struck 31 winners in his upset to avenge a three-set loss to Nishikori in Rotterdam earlier this season. "I'm very happy to finally beat Kei," the 49th-ranked Herbert said. "I was very confident with my defense. I came to the match with good feelings after the first round." Nishikori lost the Monte Carlo final a year ago to 11-time champion Rafael Nadal. Meanwhile, Alexander Zverev rediscovered traces of his best form with a 6-1, 6-4 defeat of Felix Auger-Aliassime. The German, who is based in the Principality, reached the third round as he tamed the 18-year-old who broke through for a Miami semifinal last month. The 21-year-old Zverev played the semi-finals in Monte Carlo a year ago but has yet to hit his stride this season. "This is the first time this season I've felt really healthy," said Zverev, who lost prematurely at both Indian Wells and Miami, as well as in Marrakech last week. "I've been training well but haven't been able to take that into matches. I live just 500 metres from here, I'm comfortable on this court. I'm starting to feel better about my game." The third seed will next face Italy's Fabio Fognini, who reached the third round when French opponent Gilles Simon was unable to play their match due to back problems. Greek sixth seed Stefanos Tsitsipas moved ahead, defeating Mikhail Kukushkin 6-3, 7-5. Britain's Cameron Norrie defeated Marton Fucsovics of Hungary 7-6 (7/3), 6-3. Novak Djokovic was severely tested before securing a 6-3, 4-6, 6-4 win over Philipp Kohlschreiber to survive his opening match Tuesday. The winner of the last three Grand Slams made eight double faults, dropped serve four times and smashed a racquet after losing the second set to his German opponent in the second-round encounter. The world No. 1 was relieved to avoid defeat in his first match of the clay season. "It was a difficult match, there were lots of breaks (a run of eight straight during the second and third sets)," Djokovic said. "There were lots of ups and downs. It was not the prettiest of matches. "He played well, but a win is a win. This was a tough first match of the clay season. "I had to figure out how I needed to move, this kind of match can be expected. It was probably good for me to spend so long on the court." Djokovic was able to avoid a second straight loss to Kohlschreiber after the 35-year-old beat him last month in the Indian Wells third round. Djokovic, who lives in the Principality, is playing his ‘home' event for the 13th time in 14 years, winning it in 2013 and 2015 and losing in the final on two other occasions. Kohlschreiber lost his 12th match from 13 played against top-ranked opponents, but gave as good as he got against an out-of-sorts Djokovic, who needed five match points to go through.. Elsewhere, 2014 champion Stan Wawrinka collapsed after a strong start to a 0-6, 7-5, 6-3 loss to Italy's Marco Cecchinato, who reached the French Open semifinals last year. Italian qualifier Lorenzo Sonego beat Russian eighth seed Karen Khachanov 7-6 (7/4), 6-4. — Agencies