World number one Novak Djokovic gained a routine win over 'lucky loser' Henri Laaksonen to move into the third round of the French Open.
Djokovic, who won the 2016 competition, secured a 6-1 6-4 6-3 victory on Court Suzanne Lenglen in Paris.
He is aiming for his second Grand Slam title of 2019 after winning the Australian Open in January.
The Serb will play unseeded Italian Salvatore Caruso after he knocked out France's 26th seed Gilles Simon.
Laaksonen was beaten by Sweden's Mikael Ymer in the third round of qualifying but took his place in the main draw as a 'lucky loser' after benefiting from withdrawals.
The Swiss player, ranked 104th in the world, then took advantage of that good fortune by beating Spanish qualifier Pedro Martinez in the opening round to set up a first meeting with 15-time Grand Slam winner Djokovic.
The first set only lasted 23 minutes, but Laaksonen provided more resistance in the second, breaking his opponent's serve in the sixth game. However, Djokovic twice broke Laaksonen's serve in consecutive service games to take a two-set lead.
Djokovic then broke again at the beginning of the third set to join Rafael Nadal and Roger Federer in the last 32.
Thiem and Zverev safely through
Fourth seed Dominic Thiem, the runner-up last year, also moved into round three with a 6-3 6-7 (6-8) 6-3 7-5 win over Kazakhstan's Alexander Bublik.
Bublik three times opted to play underarm serves to disrupt Thiem's rhythm, but could not beat the Austrian, who faces Pablo Cuevas after the Uruguayan's opponent, Britain's Kyle Edmund, pulled out through injury in the third set of their match.
Asked about Bublik's underarm serves, Thiem said: "It's a good choice against players like us who are so far behind the baseline. For me it was tough. I had difficulties finding the right position.
"I didn't practise [for] it but I just expect it from time to time. He won two out of three. Sometimes it's quite a good tactic. Some guys do it, him and [Nick] Kyrgios, so sometimes you have to sprint to deal with it."
It was a more routine match for Alexander Zverev as the fifth-seeded German won in three sets against Ymer with a 6-1 6-3 7-6 (7-3) victory.
That means all the top seven seeds are through to the third round, with eighth seed Juan Martin del Potro and ninth seed Fabio Fognini in action later on Thursday.
One seed that did go out, however, was 17th seed Diego Schwartzman as he lost 4-6 6-3 6-4 7-5 to fellow Argentine Leonardo Mayer.
'We've seen so many underarm serves' - analysis
Stuart Fraser, Times tennis correspondent, on BBC Radio 5 Live Sports Extra
Bublik has played underarm serves, taking some inspiration from Nick Kyrgios earlier this year. Someone made the point that they could be the first underarm serves on Chatrier since Martina Hingis 20 years ago?
This year is also the 30th anniversary of Michael Chang's famous underarm against Ivan Lendl.
Someone like Rafael Nadal stands so far back, so there is an opportunity here and there if you get enough side-spin on it to play it. We've seen it so much this year.