The second and fourth seeds both needed five sets, but there was an easier outing for the former champion
French Open: Zverev and Dimitrov survive scares to reach third round as Djokovic cruises
Second seed Alexander Zverev had to dig deep to reach the third round of the French Open after being pushed to five sets by Serbia's Dusan Lajovic on Wednesday.
Zverev, 21, is considered one of the favourites to win the tournament having arrived in Paris with two clay court titles, but he soon found himself a set and a break down against his 60th-ranked opponent.
However, the German rallied to break back twice in the second set and levelled the match. But just as it seemed he had turned the tide, Lajovic struck back in the third set to regain the lead.
Zverev, who has yet to progress beyond the fourth round of a grand slam, responded in ideal fashion, blowing Lajovic off the court over the next two sets to earn a 2-6, 7-5, 4-6, 6-1, 6-2 victory in three hours and 28 minutes.
Zverev will next face Damir Dzumhur of Bosnia-Herzegovina in the third round as he looks to become the first German man to win the title since 1937.
Another top seed was given an almighty scare when Bulgaria's Grigor Dimitrov was pushed all the way by American Jared Donaldson.
Dimitrov, the No 4 seed, needed four hours and 22 minutes to claim a 6-7, 6-4, 4-6, 6-4, 10-8 win, and will take on Spain's Fernando Verdasco in the next round.
Japan's Kei Nishikori also staged a comeback to edge out Frenchman Benoit Paire on Philippe Chatrier court, winning 6-3, 2-6, 4-6, 6-2, 6-3 in his first grand slam event since Wimbledon last year after recovering from a wrist injury.
Earlier in the day, former champion Novak Djokovic reached the third round for the 13th consecutive year by beating Spanish qualifier Jaume Munar 7-6, 6-4, 6-4.
Djokovic, the 2016 Roland Garros champion and former world No 1, is seeded 20 this year after struggling to rediscover his best form after returning from a right elbow injury.
He wasn't at his best on Court Suzanne Lenglen, but goes on to face Spain's 13th seed Roberto Bautista Agut for a place in the last 16.
The Serbian 12-time grand slam champion fired 39 winners but 33 unforced errors and was broken three times by Munar, the world 155.
"I am very happy to be here on Suzanne Lenglen and see so many people and see the support," Djokovic said.
"Jaume is a great player, he has lots of quality and good concentration. I congratulate him on a great match today."
There was an early exit for the Czech Republic's Tomas Berdych, whose rousing fightback ultimately proved in vain.
Former world No 4 Berydch was completing his first round match against Frenchman Jeremy Chardy after rain had forced the early completion of Tuesday's action.
Trailing 2-0 in sets, Berdych clawed his way back into the match to force a fifth set, only to lose the decider and leave the tournament with a 7-5, 7-6, 1-6, 7-5, 6-2 defeat.
World No 1 Rafael Nadal is back in action on Thursday when he takes on Argentina's Guido Pella in the second round.
Croatian third seed Marin Cilic, who face's Poland's Hubert Hurkacz, and Argentine fifth seed Juan Martin Del Potro, who takes on Frenchman Julian Benneteau, are also bidding to reach the third round ion Thursday.