BERLIN, July 20 (Xinhua) -- Top seed Roger Federer of Switzerland suffered a stunning defeat by Argentinean qualifier Federico Delbonis at the semifinals of ATP Hamburg Open on Saturday.

Federer ranked fifth in the world while the 22-year-old Delbonis was only 114th with his best ranking being 98.

However, unlike the ranking comparison, the match turned out to be much more balanced. The 31-year-old Federer saved two out of three break points and converted the only breaking opportunity in the opening set but lost 9-7 at the tiebreaker.

Neither managed a break in the second set and the left-handed Argentinean won the tiebreaker again at 7-4 to wrap up the 7-6 (9-7), 7-6 (7-4) victory in one hour, 53 minutes.

Delbonis will be fighting for his first career title in Sunday's final against Italy's 12th seed Fabio Fognini, who muscled out third seed Nicolas Almagro of Spain 6-4, 7-6 (7-1) in the other semifinal clash.