MIAMI -- Magneuris Sierra has only been in the Major Leagues for three days, but the 21-year-old is having a big impact on the Cardinals since being called up from Class A Advanced Palm Beach. He figured prominently on Tuesday in the Cardinals' come-from-behind 6-5 win over the Marlins.
Sierra, the Cardinals' No.7 prospect according to MLBPipeline.com, singled and scored in a four-run eighth inning that tied the game at 5, and then singled and scored what proved to be the winning run in the top of the ninth.
"I'm very happy," Sierra said. "I never expected to be here so quickly, so I'm really thankful for that. I just work hard and try to stay focused on my game."
Speed is one aspect of his game that has quickly become a focal point.
"My velocity is something I've been working on since I was a kid," Sierra said. "It's obviously what's gotten me this far and what helps me be in the big leagues right now."
Sierra dashed home with the game-deciding run on William Fowler's pinch-hit single in the ninth, sliding in ahead of the tag in blazing fashion.

"I feel so happy, as if it's the World Series," Sierra said of his sprint, which was clocked by Statcast™ at 7.24 seconds despite a modest 14.2-foot secondary lead. The dash was St. Louis' second-fastest second-to-home time this year on a play with a secondary lead of less than 15 feet.
On his ninth-inning single he went from home to first base in 3.88 seconds, helping force an error that got him into scoring position at second. Only seven players this season have recorded a faster home-to-first time on a non-bunt.
It tied Sierra's own record (set Monday night) for the Cardinals' fastest non-bunt, home-to-first time in the Statcast™ Era (since 2015).
"It's awesome to watch," Fowler said. "The guy comes up and comes right in and contributes. Speed never slumps."
Sierra helped set up the big four-run eighth inning, which tied the game, when he delivered a routine single and never stopped around first base and made it into second without a play.
"He surprised all of us," Cardinals manager Mike Matheny said. "He never slowed down. Next thing I know, he's three strides from second on a ball that's pretty much straight into the cutoff man. That was just determination out of the box to make something happen.
"As much as we try to teach it, that has to be who you are and what you do as soon as you put the bat on the ball, and not be satisfied with getting a base hit. It's one thing to have speed, but it's another thing to have that kind of desire to get that next base."
Sierra's eighth-inning hit put runners at second and third with no outs to start the rally.
"That's just showing heart and fight," Matheny said. "They came back in after we gave up those runs in the sixth inning and you could tell that they were determined to make something happen. Great at-bats all the way through, relentless at-bats."
Matheny echoed Fowler's sentiments on watching Sierra use his speed to make things happen.
"It'll make any defender rush," Matheny said. "He's doing a real nice job, staying within his game, and his game just creates opportunities for us."