Six days after the swap for the pitching ace, the former AL Cy Young Award winner gets the chance to confirm whether general manager Jeff Luhnow's move is well worth the price.
Tuesday marked Greinke's Astros debut in his start at home against the Colorado Rockies, a familiar foe from his time in Arizona and the Los Angeles Dodgers.
Greinke last pitched July 31, literally hours before that day's trade deadline, in a Diamondbacks loss at Yankee Stadium.
While he's known for his quiet but intense demeanor on the hill, Greinke, who turns 36 in October, had to wait for his start, which came after two other deadline day acquisitions, Aaron Sanchez and Joe Biagini, took part in a combined no-hitter on Saturday.
As it stands momentarily, Grienke is slated as the No. 2 starter in the rotation, bumping another legitimate ace, Gerrit Cole, to third in the order. Justin Verlander, the Astros' ace, earned a win on Sunday.
Astros fans made sure to show out for Greinke's debut. The attendance at Minute Maid Park was 43,243, which is the largest crowd this season.
Greinke would finish his Astros debut with 6 IP, 7 H, 5 ER and 2 K's. The Astros' offense supported Greinke, hitting 4 HR's, with two of them coming from Yuli Gurriel.
With the Astros' offense in full force Tuesday night, Greinke jokingly said post-game that it was kind of boring to wait out those innings, doing what he could to stay loose.
The Astros beat the Rockies 11-6 and moved to 74-40 on the season.
Astros' manager A.J. Hinch said he was impressed by how Greinke goes about his business and his preparation going into the game. Hinch noted that Greinke stayed involved throughout the game.
What to know about superstar pitcher Zack Greinke
Astros fans showing excitement with introduction of Zack Greinke