Ramirez, 22, is one of five young Mariners prospects competing in the four-team Qualifier 3 tournament in Panama City.
Right-hander Ivan Julio is on Colombia's roster, while right-hander Thyago Viera is competing for Brazil. Julio, 20, went 6-2 with a 3.11 ERA in 13 games (12 starts) for the Mariners' Dominican Summer League team last season. Vieira, 19, was 3-5 with a 6.05 ERA for the Venezuelan League Mariners.
Two infielders -- Felipe Burin and Pedro Okuda -- are also on Brazil's team. Burin, 20, batted .214 with 17 RBIs in 43 games for Pulaski in the Appalachian Rookie League. Okuda, 22, hit .274 with 19 RBIs in 56 games for the Mariners' Venezuelan Summer League club.
Ramirez is the most prominent of that group, having started eight games for the Mariners as a rookie while posting a 1-3 record and 3.36 ERA in 16 appearances overall. He is expected to challenge for a spot in the 2013 rotation.
Ramirez has been pitching for Cardenales de Lara in the Venezuelan Winter League, where he's gone 0-2 with a 4.30 ERA in 14 2/3 innings over four starts this offseason.
Brazil plays Panama on Thursday in the first game of the Qualifier 3 at Rod Carew Stadium, with Nicaragua facing Colombia on Friday. The qualifier runs through Monday, with the winner advancing to the 16-team World Baseball Classic tournament in March.
Ramirez is one of three players who spent time on the Mariners' Major League roster last year who is currently playing winter ball. Outfielder Carlos Peguero is batting .357 (10-for-28) with three home runs and seven RBIs in nine games for Gigantes del Cibao in the Dominican Winter League.
Shortstop Carlos Triunfel, a September callup with the Mariners, is hitting .222 (4-for-18) with three RBIs in 10 games for Tigres del Licey in the Dominican.
Among the club's young pitching prospects in winter ball, Danny Farquhar has a 1.42 ERA in 12 innings of relief for Lara. Farquhar was obtained from the Yankees in the Ichiro Suzuki trade last July and had four saves and a 0.54 ERA in 16 2 /3 innings for Triple-A Tacoma.
Yoervis Medina, 24, has put up 10 1/3 innings of scoreless relief in eight appearances for Lara, while Mauricio Robles is unscored on in 6 1/3 innings out of the bullpen while splitting time between Lara and Tiburones de La Guaira in Venezuela.
James Paxton, one of the Mariners' top pitching prospects, has concluded his Arizona Fall League assignment after reaching his innings limit. Paxton missed his last scheduled start with the flu and finished 1-1 with a 5.68 ERA over 12 2/3 innings in five starts with six walks and 16 strikeouts.
Several other Mariners prospects, including first-round Draft pick Mike Zunino, wrap up their AFL regular season on Thursday. Zunino was batting .289 with two home runs and 14 RBIs in 18 games after going 3-for-5 in Tuesday's action, while teammate Nick Franklin is hitting .315 with two home runs and 22 RBIs and Vinnie Catricala is at .273 with two home runs and 13 RBIs.