Roger Federer's difficult season continued today when he lost to Juan Martin del Potro in the final of the Basel Open for the second year running. The Swiss played some of his best tennis this year but it was not enough to avoid a 7-6,2-6,6-4 defeat against the powerful Argentine and his 220-kph serve. His win over Tsonga in the Australian Open quarter-finals was his only victory against a top-ten ranked opponent this year.