Zack Test and Danny Barrett helped Team USA stage a comeback from 12-0, but Argentina scored a try in added time to break American hearts in Rio on Tuesday.
The American defense opened wide right for Matias Moroni to race to touch for a 17-14 win in the first Olympic match in men’s history.
The U.S. next faces hosts Brazil at 5 p.m. EDT before rounding out group play against world No. 1 Fiji at Noon Wednesday
MORE: Full match replay
Argentina’s Axel Muller got the South Americans on the board, and Gaston Revol converted to make it 7-0 with just over two minutes to play in the first half.
That would be the score at the break, though Argentina didn’t need long to add to its advantage through a disputed knock-on that was ruled a try. Fernando Luna got the try, but wouldn’t convert. 12-0 with under five to go.
Test’s long run would end in a penalty try, and an easy conversion to make it 12-7 with the bonus of Argentina going down two men for a full minute. Barrett would score and then convert to take a 14-12 lead.