He struck out the first time up against Rockies spot starter Josh Outman, but the next trip to the plate he tripled to right field, knocking in the Dodgers' first run and recording his first big league hit and RBI.
"First pitch he threw me a fastball inside, painted it," Castellanos said Saturday. "I wasn't looking in, I was looking away and telling myself to drive the ball the other way, and I ended up getting a pitch to do so.
"I was thinking double, and then I saw it hit the wall, and I'm like, 'I'm going three.' Test my hamstring a little bit."
Castellanos was called up Thursday to take Matt Kemp's spot on the roster, and he brought a hot bat with him from Triple-A Albuquerque. He was hitting .379 with 10 doubles, four triples, five home runs, and 14 RBIs in 22 games with the Isotopes.
"We heard a lot of good things last year when we got him from St. Louis about what he was doing in Double-A and stuff like that, and just the way he played," manager Don Mattingly said. "We really didn't get a chance to see it until Spring Training. He's a high-energy guy. He's a strong kid. He's got a good look in his eye like he loves to play. You can just see it."
With outfielder Juan Rivera's return from the disabled list set to come either Sunday in Colorado or Monday in Philadelphia, the Dodgers will likely send an outfielder down, with the probable prospects either Castellanos or Scott Van Slyke, but Castellanos is making the most of his time here, and making the case to prolong it, knocking in the Dodgers' second run on Friday with a sixth-inning sacrifice fly and singling in the eighth as part of a rally setting up the Dodgers third and final run.
"He's been impressive," Mattingly said. "He had a good spring. He swung the bat good there. He works hard. He's in great shape. He's one of those guys you like. He's been impressive, to be honest with you. There's no real negatives about Alex, at this point at least."