Silvestre Varela headed in just before the end of five added minutes to keep Portugal in the FIFA World Cup and deny the United States early progress from Group G.
Nani scored early for Portugal but Jermaine Jones struck from distance just past the hour before Clint Dempsey's 81st-minute goal seemed to have won it only for substitute Varela to level. Still, Portugal are three points behind both Germany and the US; they must not only beat Ghana on Thursday and hope it is not a draw between the top two, they must also overhaul their current goal difference deficit.
There were four enforced changes for Portugal with goalkeeper Beto, left-back André Almeida and forward Hélder Postiga taking over from injured trio Rui Patrício, Fábio Coentrão and Hugo Almeida while Ricardo Costa slotted in for suspended Pepe, sent off in the 4-0 loss to Germany. But within five minutes Portugal were celebrating, Geoff Cameron slicing a clearance into the path of Nani, whose shot nestled in the roof of the net.
Clint Dempsey shot just over and Postiga then limped off to be replaced by Éder. The US, who beat Ghana 2-1 in their opener, began to press, Michael Bradley twice going close. Cristiano Ronaldo let fly from distance but could not beat former Manchester United FC club-mate Tim Howard.
Ronaldo was warming to his task and after a good run played the ball wide to Nani only for Howard to save. The Everton FC keeper was the hero again as he tipped over a shot from Éder despite being still prostrate after a Nani shot had rattled the post.
William Carvalho took over from André Almeida after half-time but Portugal's other substitute, Éder, nearly made it 2-0 in the 48th minute, shooting over. Fabian Johnson was impressing down the US right and he cut back for Bradley but his shot, with Beto beaten, was excellently blocked by Ricardo Costa. However, just past the hour a corner was cleared to Beşiktaş JK midfielder Jones whose swerving shot from outside the box gave Beto no chance.
Raul Meireles almost restored the lead immediately but Howard dived to save. However, the US were not satisfied with a point and Dempsey chested in a Kyle Beckerman cross. Ronaldo twice headed wide near the end, and just as it seemed all hope was gone, swung over a centre for Valera to nod in. The US now still need a point against Germany, coached by Jürgen Klinsmann's assistant from the 2006 finals, Joachim Löw.