HOUSTON - Emiliano Martinez saved two spot kicks as defending champions Argentina defeated Ecuador on penalties to advance to the Copa America semifinals on Thursday.

Lisandro Martinez put Argentina ahead by nodding home just after the half-hour and the Albiceleste looked on course for victory before Kevin Rodriguez equalized in second-half stoppage time.

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With no extra-time, the game went straight to penalties and Argentina looked crestfallen when Lionel Messi's opening attempt bounced off the top side of the crossbar.

But Martinez denied Angel Mena and Alan Minda before Nicolas Otamendi converted the decisive spot kick as Lionel Scaloni's men prevailed 4-2 in the shootout.

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Argentina will now meet the winner of Friday's quarterfinal between Canada and Venezuela for a place in the final.

"I wasn't ready to go home," Emiliano Martinez said afterward. "The truth is that it was a really difficult game. We knew that Ecuador was one of the toughest teams in the competition. They're a young team that defends well and fights until the end."

Ecuador began brightly at NRG Stadium and Angel Preciado shot over when he ought to have done better after smart play from Enner Valencia.

Argentina took the lead in the 35th minute when Alexis Mac Allister flicked on Lionel Messi's corner before an unmarked Lisandro Martinez headed home at the far post.

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Ecuador were handed a penalty on the hour after Rodrigo de Paul was deemed to have handled the ball inside the area. But Valencia squandered the chance to equalize by sending his spot-kick crashing off the left post.

Argentina began to push forward with more purpose and Messi forced a smart save from goalkeeper Alexander Dominguez after combining with De Paul.

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Lisandro Martinez had an attempt blocked and saw another shot sail wide as the Albiceleste continued to search for a second goal.

But the momentum swung again and Jordy Caicedo's left-footed effort went narrowly wide before Rodriguez stunned the reigning world champions by breaching Martinez's goal for the first time this tournament with a header into the bottom left corner following John Yeboah's cross.