The 11-time grand slam champion was tested for the second match in a row before defeating France's world No. 8 Jo-Wilfried Tsonga 6-3 7-6 (7-3) in Saturday's opening semifinal in one hour and 36 minutes.
Sixth seed Juan Martin del Potro eased past German Benjamin Becker 6-2 6-4 6-2, while French seventh seed Jo-Wilfried Tsonga battled to a straight-sets win over Japan's Go Soeda.
That quarterfinal was tied 1-1 after the opening day in Buenos Aires, as world No.8 Jo-Wilfried Tsonga battled to overcome 71st-ranked Carlos Berlocq 4-6 6-2 6-3 5-7 6-2 in the opening match.