Roger Federer has set up a semi-final clash with fellow countryman Stanislas Wawrinka at the Cincinnati Open after a straight-sets triumph over Mardy Fish.
The Swiss world number one broke twice to claim the opening set 6-3.
Fish fought back in the second and forced the tie-break as neither player dropped a service game.
However, Federer overcame the American 7-4 in the tie-break to reach the last four.
