Hamilton broke out of his lengthy slump at Angel Stadium with a walk-off home run in Saturday's 6-5, 10-inning victory. Los Angeles (55-67) hadn't won a division game since beating Oakland on July 25, snapping a team-record 10-game skid.
While Hamilton is batting .400 with 14 RBIs during a 10-game road hitting streak, he had been hitting .054 (2 for 37) in his previous 10 at home before Saturday's 2-for-5 performance.
"Everybody I've talked to says players go through seasons like this, and this is the first season I've ever gone through like this,'' said Hamilton, hitting a career-low .227 but with five home runs in his last 14 games against the Astros.
Teammate Mark Trumbo added his 27th home run as the Angels ended a five-game home skid to major league-worst Houston (40-82) in which they averaged 2.0 runs and hit .211.
Los Angeles looks to build on Saturday's 12-hit performance with Vargas (6-5, 3.86 ERA) starting the series finale.
Vargas showed some rust in his first start since having surgery to remove a blood clot from near his left armpit on June 26, allowing four runs and eight hits - two homers - over 4 1-3 innings in Tuesday's 14-7 loss at Yankee Stadium.
"I think he threw the ball a little better than maybe some things are going to show," manager Mike Scioscia said. "He's building into a little bit of stamina and he'll be better next time.''
The left-hander hopes to make that progression and improve on his 5-1 record and 3.13 ERA in eight home starts.
Vargas, though, did not pitch well against the Astros on May 9, allowing a season high-tying five runs and 10 hits over 5 2-3 innings before the Angels rallied late for a 6-5 road win May 9.
Jose Altuve went 3 for 3 when facing Vargas in that contest, while Matt Dominguez was 2 for 2 with three RBIs. Vargas has done a nice job against Chris Carter, who is 1 for 12 with six strikeouts in this matchup.
Carter, however, is 8 for 20 with three homers and 10 RBIs over a six-game hitting streak in Anaheim. Robbie Grossman has also been on a road tear, batting .438 during a 12-game run there.
The Astros will attempt to regroup with their fourth win in six games by giving the ball to rookie Brett Oberholtzer (2-1, 2.57).
After posting a 7.36 ERA in three relief appearances, the left-hander has been superb since joining the rotation. He's 2-1 with a 0.87 ERA in three starts and is holding opponents to a .187 batting average during that span.
Oberholtzer pitched well enough to win Monday, allowing two runs and seven hits over 6 2-3 innings in a 2-1 loss to Yu Darvish and Texas.
He might have to figure out a way to retire Mike Trout, who looks to extend his on-base streak to 40 consecutive games. The All-Star is batting .400 in an eight-game home hitting streak against the Astros.