Clint Dempsey scored his 50th international goal as the United States reignited their Copa America campaign to ease the pressure on coach Jurgen Klinsmann with a 4-0 win over Costa Rica here Tuesday.

The host nation, beaten by Group A rivals Colombia in the tournament opener on Friday, produced a devastating first half goal blitz to sink their rivals from the CONCACAF region on a warm night at Soldier Field.

Dempsey opened the scoring from the penalty spot before Jermaine Jones and Bobby Wood struck just before half-time to effectively settle the contest. Substitute Graham Zusi added a fourth three minutes from time.

The win came as a welcome relief for Klinsmann, whose tenure has faced mounting criticism over the past 18 months after a series of disappointing performances in competitive matches.

United States Soccer Federation chief Sunil Gulati had fueled fresh speculation about Klinsmann's position only hours before kickoff, telling journalists: "No-one has iron-clad job security."

Klinsmann meanwhile showed he was in no mood to cede ground to his critics, picking the same starting line-up to face Costa Rica that had disappointed in the 2-0 defeat to Colombia.

Klinsmann's faith was rewarded with a superb first half display from his team.

"I think it was, over all, a very pleasant performance," a satisfied Klinsmann said.

"It confirms the spirit of the group. They are all there for each other, the whole bench is jumping up and down when we score. Everybody wants the others to do well. It's a good group of guys that we have together.

"They deserve a huge, huge compliment for tonight's performance.

"We were eager to get on the field, eager to get our first three points of the tournament. "We took a bit to get into the game. But when the first goal came we kept pushing for the next one and the next one."

The hosts took the lead within minutes of the kick-off, when Cristian Gamboa needlessly shoved Wood in the back to concede a penalty.

Costa Rica's players protested but they could have no complaints about what was a clear-cut foul.

Dempsey then ignored a scrum of Costa Rica players around him as he stepped up to coolly ram home the spot-kick, sending Patrick Pemberton the wrong way and becoming only the second US player to score 50 international goals.

The US doubled their lead in the 37th minute with a goal that owed everything to the tenacity of Colorado Rapids midfielder Jones, who won the ball in midfield to send Dempsey into space.

The Seattle Sounders man jinked clear of one marker but looked to have taken a touch too many as Costa Rica scrambled to get back to cover.

Jones however had sprinted up in support and swept an emphatic low drive into the bottom corner beyond the dive of Pemberton for 2-0.

It got better five minutes later with another counter-attacking goal which began when Alejandro Bedoya and Dempsey combined to find Wood on the edge of the penalty area.

Wood, the Germany-based forward whose 17 goals in 31 games for Union Berlin last season helped earn him a move to Hamburg, turned his marker Oscar Duarte cleverly and then lashed home a low shot.

Costa Rica rallied after the break, and Bryan Ruiz saw his header hit the post on 67 minutes, but the United States were never in danger.

Zusi added the final home goal in the 87th minute, pouncing on a mistake to skip clear and shoot past Pemberton.

The Americans face Paraguay in their final group game where a win will guarantee them a place in the quarter-finals.