ROME (Reuters) - Unseeded Swiss Stanislas Wawrinka won an entertaining tussle with American James Blake 6-7 7-6 6-1 to go through to the semi-finals of the Rome Masters on Friday.

Wawrinka made a confident start, breaking Blake in the third game. But the American eighth seed held his nerve, broke back in the eighth game and took the first set in a tiebreak.

Blake showed more resilience in the second set, saving four set points when 5-3 down and two more in the tiebreak before Wawrinka levelled the score with a sweet backhand winner down the line.

The Swiss, who had treatment on back and leg problems at the end of the second set, used the momentum from the tiebreak win to romp home in the decider.

Wawrinka, who had beaten former world number ones Juan Carlos Ferrero and Marat Safin and Britain's Andy Murray to reach this stage, will meet the winner of the match between top American Andy Roddick and Spain's Tommy Robredo.

Roger Federer, bidding for his first Rome title, tackles Czech Radek Stepanek later on Friday.

If the world number one wins, in the semis he could be pitched against Australian Open champion Novak Djokovic, who must first get past Spain's Nicolas Almagro in the late match.