Roger Federer failed to reach the Halle Open quarterfinals for the first time Wednesday when Félix Auger-Aliassime rallied from a set down to stun the former champion 4-6, 6-3, 6-2 in the second round.

The 20-year-old Auger-Aliassime is 19 years younger than the Swiss great, who has won the Halle tournament a record 10 times. Both share the same birthday – Aug. 8.

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Canada's Felix Auger-Aliassime celebrates winning his ATP Tour Singles, Men, Round of 16 tennis match against  Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Roger Federer failed to reach the Halle Open quarterfinals for the first time Wednesday when Félix Auger-Aliassime rallied from a set down to stun the former champion 4-6, 6-3, 6-2 in the second round.

Switzerland's Roger Federer plays a forehand during his ATP Tour Singles, Men, Round of 16 tennis match against Canada's Felix Auger-Aliassime in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Auger-Aliassime next faces German Jan-Lennard Struff, who shocked top-seeded Russian Daniil Medvedev on Tuesday, or American qualifier Marcos Giron.

Canada's Felix Auger-Aliassime throws the ball to serve during his ATP Tour Singles, Men, Round of 16 tennis match against  Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime throws the ball to serve during his ATP Tour Singles, Men, Round of 16 tennis match against Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime plays a forehand during his ATP Tour Singles, Men, Round of 16 tennis match against Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime plays a forehand during his ATP Tour Singles, Men, Round of 16 tennis match against Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime reacts during his ATP Tour Singles, Men, Round of 16 tennis match against  Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime reacts during his ATP Tour Singles, Men, Round of 16 tennis match against Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Switzerland's Roger Federer plays a forehand during his ATP Tour Singles, Men, Round of 16 tennis match against Canada's Felix Auger-Aliassime in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Switzerland's Roger Federer plays a forehand during his ATP Tour Singles, Men, Round of 16 tennis match against Canada's Felix Auger-Aliassime in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Federer had been going for his 18th quarterfinal in as many appearances at the grass-court tournament, but 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.

Canada's Felix Auger-Aliassime celebrates winning his ATP Tour Singles, Men, Round of 16 tennis match against  Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime celebrates winning his ATP Tour Singles, Men, Round of 16 tennis match against Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Auger-Aliassime next faces German Jan-Lennard Struff, who shocked top-seeded Russian Daniil Medvedev on Tuesday, or American qualifier Marcos Giron.

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).

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Switzerland's Roger Federer plays a forehand during his ATP Tour Singles, Men, Round of 16 tennis match against Canada's Felix Auger-Aliassime in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Switzerland's Roger Federer plays a forehand during his ATP Tour Singles, Men, Round of 16 tennis match against Canada's Felix Auger-Aliassime in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime throws the ball to serve during his ATP Tour Singles, Men, Round of 16 tennis match against  Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime throws the ball to serve during his ATP Tour Singles, Men, Round of 16 tennis match against Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime plays a forehand during his ATP Tour Singles, Men, Round of 16 tennis match against Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime plays a forehand during his ATP Tour Singles, Men, Round of 16 tennis match against Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime reacts during his ATP Tour Singles, Men, Round of 16 tennis match against  Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Canada's Felix Auger-Aliassime reacts during his ATP Tour Singles, Men, Round of 16 tennis match against Switzerland's Roger Federer in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Switzerland's Roger Federer plays a forehand during his ATP Tour Singles, Men, Round of 16 tennis match against Canada's Felix Auger-Aliassime in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)

Switzerland's Roger Federer plays a forehand during his ATP Tour Singles, Men, Round of 16 tennis match against Canada's Felix Auger-Aliassime in Halle, Germany, Wednesday, June 16, 2021. (Friso Gentschdpa via AP)