Agnieszka Radwanska has beaten Venus Williams in straight sets to reach the semi-finals of the Sony Ericsson Open in Miami, Florida.
The world number four got off to a strong start when she broke Williams's first service game.
The American fought back and managed to exchange breaks with her opponent, before another break of serve looked as if Williams had put her recent health problems behind her.
However, Radwanska found an all-important third break before she took the opening set 6-4.
Despite a positive showing from Williams in the first, the world number 133 appeared tired in the second as Radwanska's superior fitness saw her break serve twice. A final break was enough for Radwanska to seal the set 6-1 an book a place in the last four.
