Worcester centre Alex Grove suffered last gasp international agony as Scotland's 100% record under new coach Andy Robinson came to an end as Argentina extended their winning run at Murrayfield to 19 years with a 9-6 win.
The hosts dominated the first half on Saturday but only led 6-0 at half-time through two Phil Godman penalties.
Martin Rodriguez landed two of his own to level the scores after 58 minutes and the Pumas' inside-centre clinched victory with a 77th-minute drop-goal, which means Scotland have not beaten Argentina at Murrayfield since 1990.
Scotland, for whom Grove played the entire 80 minutes again on his third appearance for his country, went into the game full of confidence after a first win in 27 years against Australia last weekend.
Warriors will take a one-point advantage back to Sixways after a Niall Annett try on the stroke of full-time handed Dean Ryan's men victory in the first leg of the Greene King IPA Championship play-off final.