PARIS - World number four Casper Ruud admitted his preparation going into the French Open has not been ideal but is counting on his experience from his final run last year and the ability to endure five setters to go deep at Roland Garros.

Ruud reached his first Grand Slam final at Roland Garros last year but the Norwegian was swept aside by Rafa Nadal in straight sets as the Spaniard won his 14th crown on the Parisian clay.

Ruud has played in six claycourt tournaments in the build-up to the French Open and won the title in Estoril, but he struggled in Monte Carlo, Barcelona and Madrid before a semi-final run in Rome and a quarter-final exit in Geneva.

"It's been going up and down, a little bit similar to what happened last year," Ruud told reporters.

"But I'm coming here with good confidence, it's best-of-five sets on clay. I have proven to myself and others from last year that I can do well and win many matches.

"It's nice being back here, live through the memories that I have from last year and the belief that I can do well here obviously grows when you have done it at least once before. I'm hoping for a good run now in these two weeks."

Ruud plays Sweden's Elias Ymer in an all-Scandinavian, first-round clash and the 24-year-old Norwegian said their friendship will be put aside when they face off after the Swede came through qualifiers without dropping a set.

"He's one of the few guys that I sometimes go out to dinner with, him and his brother (Mikael). I actually feel like a good friend off court. So it's going to be fun," Ruud said.

"He's a couple years older than me, so I really looked up to him when I was younger... He deserves to be here in the main draw and I'm going to treat him like any other opponent, a tough one."

(Reporting by Rohith Nair in Bengaluru; Editing by Kim Coghill)