Two of the top arms from the Dominican Republic are still waiting for their signed contracts to receive the approval of Major League Baseball, according to international sources.

Dominican righthander Andres Serrano, who signed with the Cardinals for $750,000 last year in October, still hasn't cleared his complete background check with the league. Serrano, who turns 18 on Tuesday, received the top bonus for a Dominican pitcher in 2011 thanks to his projectable 6-foot-3, 190-pound frame, 90-95 mph fastball and a curveball that flashes plus.

Simon Mercedes, a Dominican righthander who signed with the Red Sox for $800,000 in March, also still has a pending contract. Mercedes, 20, is 6-foot-4, 220 pounds with a 92-96 mph fastball and an average to above-average breaking ball. Mercedes had previously agreed to a $400,000 deal with the Giants in 2011, but that deal fell through after MLB investigated his background and declared him ineligible to sign for one year.

Players with pending contracts are no longer allowed to play in the Dominican Summer League, which opens on June 3.