JUPITER, Fla. -- Before Victor Mesa Jr., the Marlins' No. 14 ranked prospect per MLB Pipeline, could travel south on Interstate-95 to catch Sunday night's USA vs. Cuba World Baseball Classic semifinal matchup at loanDepot park, he had his own business to take care of.

Invited to big league camp for the day to start in center field and bat ninth, Mesa knocked the walk-off homer in Miami's 5-4 victory over Houston at Roger Dean Chevrolet Stadium. He also produced a sacrifice fly in the third inning.

"He had a couple good at-bats today -- good sac fly and the big walk-off home run," manager Skip Schumaker said. "He's handling himself the right way. What we liked the most is he's hanging around big leaguers and learning the right way, so that's what we're most concerned about. The walk-off is nice for him, but how he's growing is what we're concerned about, which is good."

Mesa ambushed the first offering from right-hander Brandon Bielak -- an inside 92.2 mph four-seam fastball -- to open the ninth. According to Statcast, the ball left the bat at 104.3 mph with a launch angle of 38 degrees.

"[Once] I hit it, I know that I just hit it well that it was gone," Mesa said. "I was just trying to go there and get a pitch that I can hit. I didn't want to swing at bad pitches, as I did in my second AB when I was a little anxious after I got good contact to the middle. In the second AB, he threw me a couple balls in the dirt and I was swinging. So I just tried to be patient and get my pitch."

Per MLB Pipeline's scouting report, the left-handed-hitting Mesa has one of the sweetest swings and some of the best feel for the barrel among Miami farmhands. A hit-over-power batter, the 21-year-old Cuban could belt 15-20 homers per season if he gets stronger and drives balls in the air more regularly. On the 20-80 scouting scale, Mesa possesses 45-grade power.

In his second full professional season in 2022, Mesa slashed .243/.323/.346 with 26 doubles, three triples and five homers in 121 games for High-A Beloit. He followed that up with two homers in 17 games at the Arizona Fall League while facing competition more than two years older than him.

"Last year, it wasn't my best, really," Mesa said. "I know that, so I just worked a lot on my speed. I go a lot to the track. I learn every day. Try to do my best, work a lot. Every time, I was waking up at like 6 [a.m.]. I've been doing a diet, too. I've got to try it, because this is only one opportunity, and you've got to show [the organization], so I want to be ready for that opportunity and do my best."

Over the past week, prospects Jacob Berry (No. 2), Yiddi Cappe (No. 7), Kahlil Watson (No. 13), Mesa (No. 14) and Ian Lewis (No. 15) have appeared in Grapefruit League games. Mesa admitted he was surprised when they told him on Saturday that he would be starting on Sunday.

"The more these young guys can come up and play in these bigger games, whether it's Eury [Pérez] or a guy like Mesa, the better [it is] for them," Schumaker said. "Just having the experience of being around our Major League guys [is important]. They're now [in the game] six or seven innings, and so he gets to watch them six or seven innings and not just two at-bats, and [then they're] out of the [game by the] fourth [inning]. That part is a lot more valuable to me than him getting a couple innings in the outfield.

"[Outfield coach] Jon Jay's been really good at making sure these guys are understanding that, and not just sitting grabbing some gum and sunflower seeds. They're actually paying attention, watching, seeing jumps, moving around and being a leader in center field -- there's just a lot more stuff than just getting an at-bat or playing a couple innings out there."