Zack Greinke had an uneven outing in his highly-anticipated Houston Astros debut, giving up five runs in six innings to the visiting Colorado Rockies on Tuesday night.

Acquired in a blockbuster trade with the Arizona Diamondbacks, the 35-year-old right-hander joined All-Stars Justin Verlander and Gerrit Cole to round out what many are calling the best starting rotation in baseball.

However Greinke, who entered Tuesday's game 10-4 with a 2.90 ERA in 23 starts this year, didn't have his best stuff.

After a solid first three innings, Greinke gave up two earned runs in the fourth and then a tying, three-run homer to Raimel Tapia in the top of the sixth. Righty Chris Devenski took over for Greinke to start the seventh.

The former Cy Young winner finished his night with two strikeouts and two walks.