* Belgium make dominance pay in extra time
* De Bruyne and Lukaku strike
* U.S. keeper Howard inspired
* Belgium face Argentina in last eight (Adds Wilmots quotes)
By Neil Maidment
SALVADOR, Brazil, July 1 (Reuters) - Extra-time goals from Kevin De Bruyne and Romelu Lukaku sealed a thrilling 2-1 victory for Belgium over a spirited United States on Tuesday and set up a World Cup quarter-final clash with Argentina.
After dominating normal time and being frustrated by an inspired Tim Howard in the U.S. goal, De Bruyne struck in the 93rd minute, collecting a loose ball before turning and firing home an angled shot from seven metres.
In a pulsating extra-time, substitute striker Lukaku powered home a second on 105 minutes after a clever De Bruyne pass before Julian Green's neat volley ensured a tense finish in which Clint Dempsey almost sneaked an equaliser.
"We had about 15 chances, we were controlling the game I think it is largely deserved even though at the end we conceded one," Belgium coach Marc Wilmots told reporters.
"My players reached their limits to qualify. I said fresh legs would be important today and that is how it was. Now the whole of Belgium can celebrate."
It could have been very different for the Belgians had U.S. substitute Chris Wondolowski not horribly skewed wide from five metres in the dying seconds of normal time to seal what would have been a smash and grab victory.
"It was heart-breaking. We left it all out there but we lost to a really good team. It hurts but hats off to Belgium they were fantastic," Howard said in a televised interview.
"Sometimes when you give your best it doesn't come off. We put them under real pressure at the end and fell short but it was an unbelievable night and we have an incredible group of players."
Belgium enjoyed nearly all the possession and looked the more dangerous side throughout as the U.S. were forced to set up camp outside their own penalty area and look to attack on the break.
On his first start in Brazil, Belgium striker Divock Origi was in on goal inside 40 seconds but his low drive was parried away for a corner by Howard, while the lively De Bruyne should have done better after 23 minutes having found space in the box.
Dempsey's tame volley represented the best chance for the Americans in the first half and they were forced to dig deep again after the interval to cope with another Belgian onslaught.
Dries Mertens and Jan Vertonghen tested Howard before Origi went close with a header that hit the crossbar. Howard was again on hand to repel Kevin Mirallas and he dealt with two more stinging Origi shots and a Vincent Kompany effort.
With extra time moments away, United States' Wondolowski missed a glorious chance that they would come to rue.
All Belgium's goals in Brazil had come after the 70th- minute mark and their persistence finally paid off in extra time when De Bruyne fired home after Lukaku raced down the right wing and centred.
De Bruyne returned the favour on 105 minutes, teeing up the frontman to power home a second which sparked a thrilling finale.
Roared on by deafening chants of 'USA', Juergen Klinsmann's side summoned the energy to raise American hopes.
Midfielder Green met a chipped Michael Bradley pass to volley home two minutes later and Dempsey almost forced penalties, only for his clever set-piece effort to be foiled by Thibaut Courtois.
The win was Belgium's fourth in four games in Brazil and sealed their first World Cup quarter-final appearance since 1986. They will play Argentina on Saturday. (Editing by Ed Osmond)