Latvala was three hundredths of a second quicker than returning world champion Sebastien Loeb across the 3.75-mile stage just outside Villa Carlos Paz.
"I'm happy with that," smiled Latvala at the end of the stage.
"I made some changes to the car after shakedown this morning - the car felt soft – so we fitted stiffer springs, but we need to go stiffer still. This is a good start."
Quickest after two practice runs in the morning, Loeb admitted to feeling a little rusty when it came to finding the limit in qualifying.
"It didn't feel natural at the start of the stage," Loeb told AUTOSPORT. "I wasn't sure on the braking point, but then it was OK."
Championship leader Sebastien Ogier was third fastest almost three tenths down and ruing one small mistake in the stage.
"I ran wide in one corner," he said, "it's small, but it cost time. The road was very soft and we just slid a little bit more than I thought we would."
Loeb's fellow Citroen drivers Dani Sordo and Mikko Hirvonen were next up with Mads Ostberg the leading M-Sport runner 1.371 seconds down on Latvala's benchmark.
None of the drivers suffered any significant problems through the stage, which determines who will run where on the road for the event's opening leg tomorrow.
Local hero Gabriel Pozzo was slowest of the World Rally Car qualifiers in his M-Sport Ford Fiesta RS WRC, 9.234s off.
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- Sebastien Loeb