Ruud, who was beaten by Rafa Nadal in last year's final, is aiming to capitalise on the 14-times champion's absence through injury this year and looked rock solid for much of his 6-3 6-2 4-6 7-5 victory over Italian qualifier Giulio Zeppieri.
"It was a tough match," Ruud said.
In a normal match I would have won 6-3 6-2, but here you have the chance to fight like he did.
That's the only reason why I'm good at tennis, because I'm half Czech."
Croatian Borna Coric was made to work hard by Pedro Cachin before the 15th seed prevailed 6-3 4-6 4-6 6-3 6-4 while it was the end of the road for Australian 18th seed Alex de Minaur who fell to a 6-3 7-6(2) 6-3 defeat by Tomas Martin Etcheverry.
Persons:
Roland Garros, Norway's Casper Ruud, Sweden's Elias Ymer, Casper Ruud, Elena Rybakina, Linda Noskova, Ruud, Rafa Nadal, Giulio Zeppieri, Mirra Andreeva, Frenchwoman Diane Parry, Kayla Day, Madison Keys, Coric, Pedro Cachin, Alex de Minaur, Tomas Martin Etcheverry, Shrivathsa Sridhar, Pritha Sarkar
Organizations:
Sweden's Elias Ymer REUTERS, Wimbledon, Thomson
Locations:
Paris, France, PARIS, Czech, Prague, Croatian