LOS ANGELES, March 10 — Felix Auger-Aliassime won the battle of the young guns by beating ninth seed Stefanos Tsitsipas 6-4 6-2 yesterday to advance to the BNP Paribas Open third round.

The 18-year-old Canadian, the youngest player in the world top 100, fired an unreturnable serve on match point to defeat the 20-year-old Tsitsipas — who is the youngest player in the top 10.

While the outcome is an upset on paper, Auger-Aliassime held a 3-0 advantage over Tsitsipas when they met as juniors.

Next up for last month’s Rio Open finalist is either Japan’s Yoshihito Nishioka or Spain’s Roberto Bautista Agut, who play their second-round match later on Saturday.

American qualifier Marcos Giron battled back to down 23rd seed Alex de Minaur 1-6 6-4 6-2.

Playing in just his fourth ATP tournament, the Southern California native settled down after a shaky first set to dispatch the Australian.

The 25-year-old will be a heavy underdog when he faces either countryman Sam Querrey or Canadian Milos Raonic, two of the biggest servers at the tournament, in the third round. — Reuters