The United States advanced to a ninth successive CONCACAF Gold Cup semi-final thanks to a first-half blitz and 2-0 win over El Salvador.

USA – semi-finalists in 2015 – had two unlikely players to thank, defenders Omar Gonzalez and Eric Lichaj, for the quarter-final victory in Philadelphia on Wednesday.

Boosted by the reinforcements of Jozy Altidore and Clint Dempsey, as well as captain Michael Bradley, it was Gonzalez and Lichaj who scored quick-fire goals to sink a spirited El Salvador outfit.

A towering header from Pachuca centre-back Gonzalez gave hosts USA the lead with four minutes of regulation time remaining in the first half.

And USA put the result beyond doubt in the second minute of additional time after Lichaj combined with Dempsey – looking more like a forward than a full-back as he doubled the lead.

Bruce Arena's USA will now meet Costa Rica for a place in the tournament decider in Santa Clara on July 26, though he will be hoping for an improved performance defensively.

USA named a completely different XI following their final Group B game against Nicaragua – a 3-0 win last week. Bradley, Altidore, Dempsey, Tim Howard and Darlington Nagbe came into the line-up, along with Gonzalez, Lichaj, Justin Morrow, Matt Hedges, Paul Arriola and Gyasi Zardes.

There was just one change for El Salvador. Having booked their spot in the last eight as one of the best third-placed teams thanks to a 1-1 draw against Jamaica, Eduardo Lara selected Alexander Larin with Ruben Marroquin making way.

USA and Lichaj made a shaky start. The Nottingham Forest defender's attempted back pass fell short and Rodolfo Zelaya pounced but Howard was quick off his line to stop the El Salvador forward in the third minute.

The Americans had a great chance themselves four minutes later. Gonzalez's shot inside the six-yard box was somehow saved by Derby Carrillo on the line and then eventually blocked for a corner after Hedges' follow-up effort.

It continued to be a lively affair as Altidore received the ball from Nagbe and turned his opponent inside the area but Carrillo was up to the task.

Fouls crept into the niggling contest, however, El Salvador continued to match it with their highly-fancied opponents, that was until USA's quick-fire double before half-time.

Gonzalez pushed up for a set-piece and rose highest to head home Bradley's free-kick and break the deadlock in the 41st minute.

And El Salvador were left shell-shocked in first-half stoppage time when Lichaj – in an advanced position on the edge of the area – was played through following a stunning turn by Dempsey and coolly slotted the ball through the legs of Carrillo.

El Salvador emerged from the break with plenty of tenacity – Denis Pineda dispossessing USA and firing a powerful low effort agonisingly wide of the post seven minutes into the second half.

The El Salvadorians then wasted a great two-on-one opportunity as they broke forward on the counter-attack. And USA continued to live dangerously as Pineda got in front of two opponents and headed over the crossbar from inside the six-yard box.