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Muller will play Comesana's fellow Argentinian and defending champion Sebastian Baez in the final after the No.5 seed came back from losing the opening set to beat Camilo Ugo Carabelli 3-6 6-1 6-1.

Should Baez win, he will become the first man to win the Rio title twice, while Muller has already made history, becoming the first Frenchman into the title-deciding match.

Muller has beaten an Argentinian in each of his past three matches, upsetting No.8 seed Tomas Martin Etcheverry and No.4 seed Francisco Cerundolo.

Indeed he is 10-0 on clay against players from the South American country, and will hope to make that 11-0 against Baez on Monday (AEDT).

But that won't be easy as Baez in on a roll, although he did have to respond to a slight scare after losing the opening set to Carabelli.

That response was emphatic, seeing him win 12 of the next 14 games to advance to a ninth ATP Tour final.

“I’m so proud, because the last weeks were a little tough for me,” Baez, the only remaining seed, said.

"I didn’t feel very well this week, so I am happy to [have] recovered my body, my mind, my tennis.”