STUTTGART, Germany — Two of three Canadians won first-round matches on Tuesday at the Stuttgart Open.

Sixth seed Milos Raonic of Thornhill, Ont., and No. 7 seed Felix Auger-Aliassime of Montreal advanced to the second round of the ATP Tour 250 event, while No. 8 seed Denis Shapovalov of Richmond Hill, Ont., was eliminated by a familiar foe in the opening tournament of the grass-court season.

Shapovalov lost 7-5, 6-4 to Jan-Lennard Struff in a rematch of a French Open first-round match won by the German in straight sets. Struff, ranked 38th in the world had 14 aces in his latest win over Shapovalov.

The 18-year-old Auger-Aliassime, playing his first ATP Tour match on grass, beat world No. 90 Ernests Gulbis of Latvia 7-5, 6-3.

Auger-Aliassime, who reached a career-high No. 21 in the world rankings this week, dropped out of the French Open with a left abductor injury after advancing to the final of the Lyon Open the previous week.

Auger-Aliassime will meet France's Gilles Simon the second round.

Raonic, playing for the first time since suffering a right knee injury in late March, hit 31 aces to edge Australian qualifier Alexei Popyrin 6-7 (6), 6-4, 7-6 (4). The Canadian was dominant with first serve, winning 47 of his 50 points.

Raonic, the runner-up in Stuttgart last year, will face France's Jo-Wilfried Tsonga in the second round.