MIAMI -- At the start of Spring Training, Marlins chief executive officer Derek Jeter informed the team there would be plenty of opportunity, and based on competition the best 25 would make the club. The players took notice, and after a competitive six weeks of camp, the organization announced its Opening Day roster on Thursday.

Manager Don Mattingly will have 13 pitchers and 12 position players at his disposal when the Marlins face the Rockies at 4:10 p.m. ET at Marlins Park.

Catcher (2): Jorge Alfaro, Chad Wallach

Acquired from the Phillies as part of the J.T. Realmuto trade, Alfaro missed most of Spring Training due to a bruised right knee. The 25-year-old is healthy, but his timing may be a little off early in the season as he gets up to speed. Wallach is strong defensively behind the plate and works well with the pitchers. He grades extremely high in pitch-framing metrics.

First base (2): Neil Walker, Martin Prado

A free-agent signee and veteran leader, Walker will get a majority of the action at first base. He’s a switch-hitter, so he can also face left-handers. However, Prado is an option to play first against southpaws. Adjusting more regularly to first base will be something to watch for them both. Walker was a second baseman much of his career, and Prado was at third base.

Second base (1): Starlin Castro

A four-time All-Star, Castro enters his second season with the Marlins. He is one of the top hitters on the club and projects to hit in the middle of the order, perhaps third or fourth. Castro had 32 doubles, 12 home runs and 54 RBIs last season. If he has a strong first half, he could become a potential trade candidate.

Third base (1): Brian Anderson

One of the faces of the franchise, Anderson has moved back to third base after appearing in 70 games at the position in 2018 compared to 89 in right field. Anderson finished fourth in the National League Rookie of the Year Award voting last year, and is primed for a big second full season.

Shortstop (2): JT Riddle, Miguel Rojas

Both are expected to get plenty of playing time. Riddle, a left-handed hitter, was limited to 102 games last year because he was recovering from left shoulder surgery in 2017. Rojas, a right-handed hitter, will share time with Riddle, but he also plays second base, third and first. Rojas is coming off his best offensive season -- .252 with 11 home runs and 53 RBIs.

Outfield (4): Lewis Brinson, Garrett Cooper, Curtis Granderson, Rosell Herrera

After a sluggish rookie season in which he batted .199 with 11 home runs and 42 RBIs, Brinson will be the regular center fielder. But he may be on a shorter leash this year. Not unexpected, Granderson made it as a non-roster invitee, and the 38-year-old will lead off regularly against right-handers. Cooper was the surprise in Spring Training, rebounding from right wrist surgery to bat .395, and win the right-field job. Herrera, a switch-hitter who played briefly for the Reds and Royals last season. He can play all three outfield spots as well as the infield.

Starting pitchers (5): José Ureña, Trevor Richards, Pablo Lopez, Sandy Alcantara, Caleb Smith

Projected to be the strength of the club, the rotation will feature Urena and four talented starters who all were rookies in 2018. For the second straight season, Urena is the Opening Day starter. The right-hander stepped up in the second half last year and finished with a team-high 31 starts and 174 innings. Richards has a plus changeup, and improved his stock by adding a curveball to his mix. Lopez added eight pounds of muscle since last year, and his fastball touched 97 mph in the spring. Alcantara throws 98-mph-plus, and if his command is on, has top of the rotation ability. Smith proved healthy after undergoing left lat surgery last July.

Relief pitchers (8): Sergio Romo, Drew Steckenrider, Adam Conley, Tayron Guerrero, Wei-Yin Chen, Austin Brice, Tyler Kinley, Nick Anderson

The Marlins will play matchups in the late innings, and in save situations. But Romo, who won three World Series rings with the Giants, may get the most save chances. Conley impressed in Spring Training, with the lefty touching 97 mph and pitching with more conviction. Steckenrider is another closer option. Guerrero is the hardest-thrower of the group, regularly reaching 100 mph. Chen has moved from the rotation to the bullpen, and is a spot starter candidate. Brice, Kinley and Anderson are hard-throwing right-handers.

CATCHERS
C Jorge Alfaro
C Chad Wallach

INFIELDERS
1B Neil Walker
2B Starlin Castro
SS Miguel Rojas
3B Brian Anderson

OUTFIELDERS
LF Curtis Granderson
CF Lewis Brinson
RF Garrett Cooper

UTILITY PLAYERS
INF Miguel Rojas
INF Martin Prado
OF/INF Rosell Herrera

STARTING PITCHERS
RHP Jose Urena
RHP Trevor Richards
RHP Pablo Lopez
RHP Sandy Alcantara
LHP Caleb Smith

RELIEF PITCHERS
RHP Sergio Romo
RHP Drew Steckenrider
LHP Adam Conley
RHP Tayron Guerrero
LHP Wei-Yin Chen
RHP Tyler Kinley
RHP Austin Brice
RHP Nick Anderson

INJURED LIST
RHP Riley Ferrell (right biceps tendinitis)
RHP Julian Fernandez (60-day IL, Tommy John surgery)