The Yankees catching prospect did not look good hacking at three straight changeups from Miguel De Los Santos in the opening inning.
"I looked pretty bad, but I knew he'd come to me with another changeup, at least one," Murphy said. "I sat on that change and put a good swing on it."
Murphy whacked the fourth changeup he saw for a grand slam, sparking a memorable night during which he drove in nine runs to flirt with a South Atlantic League record as the Charleston RiverDogs crushed the Hickory Crawdads, 18-4.
The 2009 second-round pick followed his grand slam with a three-run blast in the fourth and knocked in former first-rounder Slade Heathcott with a groundout in the sixth and a single in the eighth.
"Obviously, it's pretty nice, but you've gotta be put in the right situation," Murphy said. "I had guys on base in front of me, that had everything to do with it."
It also helped that Murphy, only 19, practically knew what pitches were coming. After burning De Los Santos on that changeup, he said he knew what was on tap for his third plate appearance.
"He fell behind again and he got into a fastball count," said Murphy. "I didn't think he'd come with another change, so I got a good pitch to hit again. He's got real good stuff, but he made two mistakes and I happened to get him."
Could Murphy blossom into yet another prized catcher in the Yankees' system? In Jesus Montero and Austin Romine, the organization already has candidates to replace Jorge Posada. Murphy, who signed for $1.25 million after New York drafted him 76th overall out of The Pendleton School in Bradenton, Fla., could make a name for himself.
"I'm definitely learning some more stuff about myself and about how the pitchers are attacking me and stuff like that," he said, "about the type of hitter I am and what I can do.
"Pressure? I don't think so, really. I don't know what they're expecting of me, but they gave me the opportunity to come here to Charleston. I struggled at first a little bit, but I've gotten adjusted really well. I don't think the pressure was there much."
Murphy has been hot in August with hits in 13 of his last 14 games. He's batting .321 this month, having raised his average from .236 on July 15 to .268.
Murphy had a chance to break the league RBI record when he came up with two runners in scoring position. But he struck out, leaving intact the mark set by Asheville's James Barbe, who drove in 10 runs on April 22, 1978.
Ben Heath took his own shot at the record on Friday, homering three times and plating seven runs in Lexington's loss to West Virginia.
It was Murphy's biggest game in the Minors, eclipsing a four-RBI effort against the Tourists on July 5. He appeared in only nine games last summer, knocking in seven runs in the Rookie-level Gulf Coast League.
"It's definitely something I'll remember," he said. "I've already gotten calls and texts from my family -- my mom, who listens to every game on the radio. Hopefully, it happens again, but you never know. You gotta enjoy it when it happens."
It was Murphy's first career multi-homer game, the RiverDogs' first grand slam since 2008 and the most productive game for a Charleston batter since the club began its affiliation with the Yankees in 2005.
"Days like this are much-needed, especially the way we've been going the last month or so," Murphy said. "You gotta have some fun with it."