Yamaha rider Rossi came out on top in a last-lap duel against Ducati's Andrea Dovizioso at Termas de Rio Hondo to finish second, just under 10 seconds in arrears of runaway winner Marquez.
Although Rossi said he rode like 'when he was young' in Argentina, speaking to Italian media he remained somewhat downbeat that he couldn't offer a sterner challenge to Marquez.
"I am happy to be third in the championship behind Marquez and Dovi, who are the favourites," said the 40-year-old, who lies 14 points adrift of Marquez. "But I think we must take things race-by-race.
"There’s a good group in Yamaha and we are working hard, but the challenge is very difficult. The two of them [Marquez and Dovizioso] surely remain the favourites, so we must try to work to be competitive and fight.
"And maybe stay closer to Marquez, because to finish 10 seconds down is huge. I would have preferred to be only three seconds behind and see him sometimes.”
Andrea Dovizioso, Ducati Team
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