BOSTON, June 12 (Reuters) - Guatemala reached the quarter-finals of the Gold Cup on Tuesday after drawing 1-1 with Trinidad and Tobago, while the United States made it three wins out of three by beating El Salvador 4-0.The United States, who had already qualified for the next round before Tuesday's game, finished top of Group B with the maximum nine points, while Guatemala qualified second with four. Guatemala had two efforts disallowed before going ahead in the 80th minute thanks to a smart finish from striker Carlos Ruiz. But their Caribbean opponents drew level within three minutes, towering forward Errol McFarlane rising well to head home a cross from the right. McFarlane then missed an even easier chance in the final moments of the game, heading wide from close range after being left unmarked. In the earlier game, DaMarcus Beasley put the United States ahead in the 32nd minute, driving home after El Salvador failed to deal with a corner. LA Galaxy striker Landon Donovan made it 2-0 with a re-taken penalty on the stroke of halftime before the impressive Beasley started a counter-attack that led to the third goal, converted by Taylor Twellman. Beasley, who plays for Dutch side PSV Eindhoven, added his second and his team's fourth with two minutes remaining, coolly finishing after a clever pass from the outstanding Clint Dempsey. Bob Bradley's side, defending champions in the tournament that brings together teams from North and Central America and the Caribbean, play their quarter-final on Saturday. The group stage is completed on Wednesday when Cuba play Honduras and Mexico take on Panama -- both games are to be played in Houston.