With Jason Hammel and Pomeranz starting the final two games in Houston, the A's will head to Anaheim with Sonny Gray, Jon Lester, Scott Kazmir and Jeff Samardzija in line to face the Halos in a crucial four-game set.
"Also, it's about giving some guys that we've been leaning on a bit harder a little bit of extra rest," Melvin said. "Drew's done a nice job for us, so it's definitely a combination of things, but certainly we don't take [the Astros] lightly because they beat us two out of three last time here, and it's a much better team that has given us fits this year."
Pomeranz was 4-3 with a 3.21 ERA in eight starts for the A's before he punched a wooden chair and broke his right hand in June. The lefty rehabbed with Triple-A Sacramento, where he remained once healthy, and is 3-1 with a 3.69 ERA in eight starts for the River Cats.
Pomeranz has already faced the Astros once this year but in a relief role, firing two scoreless innings on April 24.
Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.