Guatemala's Manuel Leon celebrates his goal against Paraguay in a friendly at RFK Stadium. The teams tied, 3-3. In the second half of the doubleheader, Jamaica defeated El Salvador, 3-0. (Nick Wass/AP)

RFK Stadium was a mosaic of colors, rhythms and engaging soccer Wednesday night as four visiting national teams gathered for a doubleheader to prepare for respective World Cup qualifiers next month.

While the United States was stunning Mexico in a high-octane friendly at Azteca Stadium in Mexico City, Jamaica, the Americans’ next opponent in regional qualifying, enjoyed its tour of the U.S. capital by defeating El Salvador, 2-0, in front of 14,185 spectators.

Midfielder Luton Shelton, Jamaica’s all-time leading scorer, struck in each half for the Reggae Boyz, who will host the United States in Kingston on Sept. 7.

Jamaica and the United States are tied atop Group A with four points apiece through two of six matches each. They’ll also collide Sept. 11 in Columbus, Ohio. Two teams from the four-nation group will advance to next year’s final round of CONCACAF qualifying for the 2014 tournament in Brazil.

“It was good preparation for our U.S. game,” said Reggae Boyz Coach Theodore Whitmore, whose team will have another tuneup Aug. 25 against Kenya in East Hartford, Conn. “Anything we do now is towards the USA game. We know it’s going to be a tough game, but it’s preparation. We are preparing ourselves to beat this U.S. team.”

Jamaica went ahead in the 16th minute when Shelton toyed with Isidro Gutierrez and thumped an angled shot past Dagoberto Portillo.

The Salvadorans, supported by a majority of the crowd, had two quality chances in the first half and threatened to equalize early in the second, but Shelton headed in Ryan Johnson’s cross in the 66th minute to crush their spirits.

Johnson was among seven MLS players in the starting lineup for Jamaica, which was missing several English-based candidates. Vancouver’s Darren Mattocks and Dane Richards entered in the second half.

Former D.C. United midfielders Eliseo Quintanilla and Cristian Castillo started for El Salvador (0-1-1 in Group B), which must win its next two qualifiers, both against Guyana (0-2-0), to maintain hopes of advancing. Mexico and Costa Rica are heavily favored to top that group.

Guatemala, another U.S. opponent in Group A, began the RFK festivities with an encouraging result: a 3-3 draw against Paraguay, which featured 11 players from the 2010 World Cup squad that reached the quarterfinals.

The match got off to a crackling start as Paraguay’s Oscar Cardozo pounced on a deflection and tucked a low shot from 12 yards into the left corner after just 55 seconds.

Guatemala answered in the eighth minute when Marco Pappa (Chicago Fire) converted a penalty kick. Carlos Ruiz, a former MLS MVP notorious for his embellished falls, was legitimately knocked down from behind.

The Chapines — who have one point in World Cup qualifying and will play Antigua and Barbuda in their next two matches — went ahead in the 30th minute when Manuel Leon settled Pappa’s set-up and half-volleyed a 17-yarder to the far corner.

Paraguay had a ferocious response in the second half.

Substitute Jonathan Fabbro’s 25-yard free kick in the 53rd minute caromed off the defensive wall and into the far corner. Eleven minutes later, Fabbro supplied Hernan Perez on the right side of the box for a hard-driven eight-yarder.

The Guaranies missed several chances to secure victory, and when Victor Caceres handled the ball in the box in the 84th minute, Ruiz converted the penalty kick for the 50th goal of his international career.

Off to a 1-3-1 start in South American World Cup qualifying, Paraguay will visit Lionel Messi and Argentina (3-1-1) on Sept. 7 and host Venezuela (2-2-2) four days later.