NEW YORK -- Watching Yordan Alvarez hit, it's difficult to believe he's a rookie with only two weeks of big league experience under his belt.

The Astros' 21-year-old slugger continued to impress Sunday, drilling a two-run home run against lefty J.A. Happ, the knockout punch that ended the Yankees starter's afternoon in Houston's 9-4 victory at Yankee Stadium.

It was the seventh home run for Alvarez in the first 12 games of his career, establishing an Astros franchise record and becoming only the fourth player in history to accomplish that feat.

"We heard a lot of good things about him," Jose Altuve said of Houston's No. 3 prospect. "That's one thing, but it's another thing actually watching him play and execute every swing. He has a bright future, and he's going to be a big part of this team."

Alvarez has also driven in 16 runs, which makes him the only player in history with at least seven homers and 16 RBIs through 12 games, according to the Elias Sports Bureau.

"His bat is special," Justin Verlander said. "His pitch recognition, his approach at the plate is so far advanced for his age. It's been impressive to watch from Day 1."

Even Alvarez, who led the Pacific Coast League with 23 home runs and 71 RBIs in 56 games with Triple-A Round Rock before being promoted on June 9, is somewhat surprised by his immediate success in the Majors.

"I've been hitting so many home runs early in my career, it is surprising," Alvarez said. "But it's not surprising in the sense that I've been working really hard to get to this point and to get to the big leagues. ... Just doing the same job that I've always done. Same as the Minor Leagues, just trying to do the same in the big leagues."

Alvarez went 6-for-18 with three home runs and seven RBIs in the four-game series against the Yankees. Although the Astros dropped the first three games, Sunday's win sent them back to Houston on a high note, giving the team something to build on when Tuesday’s homestand begins.

"He's mature beyond his years with his approach, his demeanor and his comfort in the big leagues," manager AJ Hinch said. "He's getting really good at hunting pitches, and when he gets them, he's doing a ton of damage. That ball that he hit out was off the plate, chasing him in a little bit. He just continues to stay balanced and hit the ball really hard. He's a really, really good hitter that understands his happy zones and where to get after it when they pitch him there."