Del Potro, the 2009 US Open champion, was a class above in his 6-4 6-2 victory in the semi-final in Acapulco.

The Argentine star overcame 2016 Mexican Open winner and No.3 seed Dominic Thiem in a blockbuster quarter-final.

Del Potro was not broken in the final-four showdown, which lasted an hour and a half, as he converted three of his own against the talented German.

Standing in the way of the No.6 seed and glory in Mexico is in-form South African Kevin Anderson.

Anderson stayed red hot with a 6-3 4-6 6-3 win over qualifier Jared Donaldson.

Seeking back-to-back titles after taking out the New York Open a fortnight ago, No.5 seed Anderson improved to 11-2 for the season after outlasting the American.

"It's another opportunity for me," Anderson said. "I'm looking forward to it. I feel like I'm playing great tennis. [It's] just about recovering and resting up right now and being as prepared as possible for tomorrow [Sunday AEDT]."

Meanwhile, three-time defending champion Pablo Cuevas kept his quest for a four-peat alive by overcoming Leonardo Mayer 6-2 6-7 (11-13) 7-6 (7-5) at the Brasil Open.

Cuevas, the No.3 seed, won 112 total points in the quarter-final contest as he extended his winning streak to 15 matches in Sao Paulo.

No.1 seed Albert Ramos-Vinolas, however, lost 6-7 (6-8) 6-4 7-6 (7-3) against Nicolas Jarry.

No.2 seed Fabio Fognini, from Italy, accounted for Guillermo Garcia-Lopez 6-4 6-2, while Horacio Zeballos prevailed 6-7 (3-7) 6-2 6-4 against Rogerio Dutra Silva.