Mexico sealed their Group A victory in the CONCACAF Gold Cup with a 4-1 triumph over Costa Rica. Andres Guardado scored twice, and Rafael Marquez and Pablo Barrera added a goal apiece for Mexico, the defending champions who won all three of their Group A matches despite a squad reduced to 17 players after five were withdrawn by Mexican football authorities after positive drug tests last month. The Mexican football federation is blaming the positive tests for clenbuterol on contaminated meat and has asked to replace the players, but CONCACAF officials have asked for more information before making a decision. Costa Rica finished second in Group A ahead of El Salvador, who trounced Cuba 6-1 earlier on Sunday. Both Costa Rica and El Salvador finished with four points, but the Costa Ricans hold the advantage on goal difference and sealed their quarter-final spot. So far Mexico haven\'t shown any sign that the absence of five players is hurting them. Their 14 goals so far are the most of any team in the tournament, which is the regional championship for North and Central America and the Caribbean. Costa Rica were expected to pose Mexico\'s toughest challenge in the group, but Marquez in the 16th and Guardado in the 19th staked Mexico to a quick 2-0 lead. Guardado scored again in the 25th, firing beneath one defender and Costa Rican keeper Keylor Navas. Barrera\'s 38th-minute strike was all that Mexico needed to round out their night, to the delight of the largely pro-Mexico crowd of 62,000 at Soldier Field. Urena\'s lone goal for Costa Rica in the 68th was the only goal Mexico conceded in group play. The top two teams in each of the three groups as well as the two best third-placed teams advance. El Salvador got the victory they needed to keep their hopes alive as Rodolfo Zelaya delivered a goal in each half in the victory over Cuba. Osael Romero, Lester Blanco, Arturo Alvarez and Eliseo Quintanilla also scored for El Salvador. Cuba finally got their first goal of the tournament when Jeniel Marquez scored in the 82nd minute, but it couldn\'t prevent Cuba from exiting the tournament having conceded 16 goals. Zelaya opened the scoring in the 11th minute with a left-footed shot from outside the area that trickled toward the net then rolled under the hands of diving Cuban keeper Julio Ramos Pichardo. Romero volleyed the ball over Ramos Pichardo to double the score in the 28th. A three-goal burst in the second half began with Blanco\'s left-footed shot in the 69th, followed in the 70th by Zelaya\'s second strike. No sooner had Marquez put Cuba on the board than Alvarez responded for El Salvador, who got one last goal from Quintanilla in the final minute. \"We\'re waiting on the other results,\" Zelaya said. \"Hopefully we were able to get the goals to move forward.\" Group play continues on Monday, when Jamaica and Honduras battle for the Group B crown and Guatemala play Grenada. Group play concludes on Tuesday when Group C leaders Panama take on Canada and the United States play Guadeloupe. The winners of the tournament secure a berth in the 2013 FIFA Confederations Cup.