Argentine qualifier Federico Delbonis dealt Roger Federer another disappointing loss, stunning the Swiss great 7-6 (9-7), 7-6 (7-4) Saturday in the semifinals of the German Open in Hamburg.

The 114th-ranked Argentine edged the 17-time Grand Slam champion in one hour and 53 minutes thanks to rock-solid play from the baseline and impressive composure in critical moments of the match.

The two players traded breaks of serve early on and the first set came down to a tiebreak, which Delbonis won by rallying from 2-4 down.

The top-seeded Federer, a four-time winner in Hamburg, encountered more trouble on his serve in the second set than his opponent, but he managed to stave off all four break points he faced to force another tiebreak.

The 22-year-old Delbonis, however, took control of that decider and secured victory on his first match point.

The Hamburg event was the 31-year-old Federer's first since switching to a new, bigger racquet after a shocking second-round loss at Wimbledon to another unheralded player, Ukraine's Sergiy Stakhovsky.

That early exit dropped his ranking to No. 5, his lowest spot in a decade.

The loss to Stakhovsky, then ranked No. 116, also marked the first time Federer had been defeated prior to the third round of a Grand Slam event since the 2003 French Open.

Next up for Delbonis in Sunday's final will be Italy's Fabio Fognini, who upset third-seeded Spaniard Nicolas Almagro 6-4, 7-6 (7-1).

Delbonis will be seeking to become the fourth Argentine to win the Hamburg title after Guillermo Vilas in 1978, Guillermo Coria in 2003 and Juan Monaco last year.

The German Open used to be a major tune-up for the French Open but has been a lesser-tier event since 2009. EFE