PARIS -- Canada's Felix Auger-Aliassime and Steven Diez both are out of the French Open after suffering first-round losses on Monday.
Auger-Aliassime, the No. 19 seed from Montreal, lost 7-5, 6-3, 6-3 to world No. 52 Yoshihito Nishioka of Japan at the clay-court Grand Slam.
Diez, a qualifier from Toronto, lost 4-6, 6-3, 6-3, 6-4 against American Mackenzie McDonald in his main-draw debut at a Grand Slam.
The loss for Auger-Aliassime continued a disappointing clay-court season for the 20-year-old Canadian. Since transitioning to the clay after a run to the fourth-round at the U.S. Open, Auger-Aliassime has won just one of four matches.
Auger-Aliassime had 58 unforced errors, 24 more than Nishioka.
Nishioka is now 2-0 lifetime against Auger-Aliassime. The Canadian lost a third-set tiebreaker to Nishioka in Indian Wells, Calif., last year.
"Today was tough for me overall, what he was bringing in the match," Auger-Aliassime said after his French Open debut. "I knew him, knew it was going to be tough to go through him, (he was) going to put a lot of balls back. Obviously the conditions were not the best for me. ... He played good.
"Also, you know, I wasn't good, and I could have been better on many of those opportunities. So, you know, I give him credit and I take responsibility on that because I just felt like there is too many times where I just didn't step up and play a decent point."
Auger-Aliassime added the result was "difficult to accept."
Later Monday, Leylah Annie Fernandez of Laval, Que., was to face No. 31 seed Magda Linette of Poland in a first-round women's match. Fernandez, 18, won the French Open girls' title last year.
No. 9 seed Denis Shapovalov of Richmond Hill, Ont., and Vancouver's Vasek Pospisil are scheduled to play their first-round matches on Tuesday.
Eugenie Bouchard of Westmount, Que., won her first-round match on Sunday.