Roger Federer failed to qualify for the Halle Open quarterfinals on Wednesday as 20-year-old Felix Auger-Aliassime rallied from a set down to stun the former champion. The Swiss great was beaten 4-6, 6-3, 6-2 in the second round. Federer, who has lifted the trophy in Halle a record 10 times, is 19 years younger than Auger-Aliassime. Incidentally, the duo also shares the same birthday on August 8. Federer was unable to deal with his young opponent’s change of tactics in the second set. Auger-Aliassime targeted the backhand with his strong serves and the Canadian player converted three break opportunities to win in 1 hour, 45 minutes. "In the first set, I didn’t think I could have played much better outside of just missing one forehand in my service game and then he hit two amazing passing shots and I was just like 'Whoa,’" Auger-Aliassime recalled to ATP tour after the match. "I understand how good he is and how good he was when he was No. 1 in the world, so it was tough," he added. Auger-Aliassime next faces German Jan-Lennard Struff, who shocked top-seeded Russian Daniil Medvedev on Tuesday, or American qualifier Marcos Giron. "I never expected to play him." Now @felixtennis has not just played, but defeated Roger Federer. #NoventiOpen pic.twitter.com/xe6eskcSJt — ATP Tour (@atptour) June 16, 2021 Stunning 🔥@rogerfederer #NoventiOpen pic.twitter.com/cnGXkXenJ6 — Tennis TV (@TennisTV) June 16, 2021 Felix fires past Federer 👀 A huge win for 20 y/o 🇨🇦 @felixtennis who defeats 10x @ATPHalle champion Roger Federer 4-6, 6-3, 6-2 👏 #NoventiOpen pic.twitter.com/5tQfM7aQ2J — ATP Tour (@atptour) June 16, 2021 Also Wednesday, Andrey Rublev defeated Australia’s Jordan Thompson 6-4, 6-4 and veteran home favorite Philipp Kohlschreiber beat Corentin Moutet of France 6-4, 7-6 (4).