HALLE, GERMANY -- Roger Federer failed to reach the Halle Open quarterfinals for the first time Wednesday when Felix 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.

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.

Auger-Aliassime next faces American qualifier Marcos Giron, who later rallied to beat Germany's Jan-Lennard Struff 6-7 (1), 6-3, 6-4.

Struff had shocked top-seeded Russian Daniil Medvedev on Tuesday.

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).