Clint Dempsey struck again as the United States powered through to the semi-finals of the Copa America Centenario on Thursday in a stormy 2-0 win over Ecuador that saw both sides finish with 10 men.

Dempsey scored his third goal in as many games for Jurgen Klinsmann's side at CenturyLink Field, pouncing on 22 minutes before setting up a second for Los Angeles Galaxy forward Gyasi Zardes in the 65th minute.

Michael Arroyo pulled a goal back for Ecuador in the 74th minute to set up a frantic finale, but the US held on and will now face either Argentina or Venezuela in the semi-finals in Houston next week.

Man-of-the-match Dempsey said the hosts were determined to extend there stay in the tournament beyond the semis.

"Hopefully we can keep going, we're in the semi-finals of a major tournament so we're happy," Dempsey said.

"This is what you dream about as a kid. We're going to keep wishing, we're going to give everything we can, we're going to try and get to the final, we want to win it.

"You don't get many opportunities to go all the way in a major tournament and that's what we're trying to do."

But the victory came at a cost for Klinsmann's side, as key midfielder Jermaine Jones was sent off early in the second half to earn a suspension which will see him miss the semi-final.

France-based midfielder Alejandro Bedoya and Hamburg striker Bobby Wood also earned yellow cards that will see them suspended for the last four.

Klinsmann was furious at the manner of Jones' dismissal, which he branded "an absolute joke."

"I was right there -- the fourth official made the decision, not the referee, he didn't see it," Klinsmann said. "He followed the decision of the fourth official. It's a disgrace, a decision like that."

For Ecuador, Manchester United's Antonio Valencia was dismissed after picking up two yellow cards before triggering the melee which led to Jones' dismissal.

Earlier, a cagey start had seen both sides begin tentatively before Jones and Michael Bradley steadily imposed themselves in midfield as the US started to gain the upper hand.

Wood's speed troubled the Ecuador defense on 17 minutes, when he darted onto a low pass only to prod his finish well wide of the advancing Alexander Dominguez.

Yet five minutes later the US took the lead with a beautifully worked goal that began when Dempsey gathered in midfield and released Wood, who fed Jones near the edge of the area.

The midfielder picked out Dempsey with a superb cross and the former Tottenham and Fulham stalwart duly headed home.