He simply walked up to the plate in the bottom of the 12th inning of the 4-4 ball game with one thing in mind: swatting the game-winning hit.
And he delivered straight from the dugout.
The veteran second baseman had runners on second and first base with one out in the frame as he eyed Brewers reliever Jorge Lopez. He smacked the righty's first offering to left field, prompting Garrett Cooper to hustle in from second, beating out a throw from Christian Yelich and winning the game.
"I didn't really go to the on deck circle and get a couple swings, I just went straight to the plate," Castro said after the 5-4 victory.
The Marlins won the three-game series 2-1 against the National League leaders. Miami (39-56) led 4-2 entering the eighth inning, but surrendered two runs in relief to prompt extra innings. Both bullpens kept the bats frozen late in the game, before Castro's heroics.
"They came back in the eighth inning to tie the game, but the pitching kept the game tight. Finally ... I'm the hero and I won the game," Castro said with a laugh.
The Brewers (55-38) capitalized on a leadoff walk from Marlins starter Dan Straily to start the game when Jesus Aguilar lined a double to left field, scoring Eric Thames from second base. Yelich -- who had four RBIs in the Brewers' win Tuesday against the Marlins -- gave his team a 2-0 lead with an RBI single off of Straily in the top of the third inning.
Then Miami mounted its comeback. Castro plated the Marlins' first run with an RBI single in the bottom of the fourth frame. First baseman Justin Bour laced a solo home run to right field in the same frame, tying the score at 2-2.
Miami earned a 3-2 advantage when Straily took a walk with the bases loaded later in the inning. The Marlins increased that lead to 4-2 when catcher Bryan Holaday singled to left field in the bottom of the sixth inning, bringing in Martin Prado.
Aguilar did more damage in the eighth inning, hitting a ground ball double to left field to score Thames and Yelich, tying the contest. Marlins reliever Drew Steckenrider blew a save opportunity by allowing Aguilar's double. Marlins right hander Elieser Hernandez picked up the victory in relief.
"We don't win these [extra inning games] by hitting a homer," Marlins manager Don Mattingly said. "We've been winning these by getting a hit ... J.T. gets a guy in scoring position and you get a hit. Instead of thinking home run, that gets you in trouble."
The Marlins have the day off on Thursday, before beginning a three-game National League East series against the division leading Philadelphia Phillies.
"It's a little disappointing," Mattingly said. "We had a two run lead late in the eighth and you don't want to end up in this game. When you are playing a team that's in first place and they are fighting for everything, they are not going to give in. They aren't going to quit. So you know they are going to keep fighting until the end."