Battling the Angels for the top spot in the American League West, the Athletics will send Jason Hammel to the mound seeking a second straight victory over the Astros with hopes that an extended rest period has helped the scuffling right-hander regain his form.
Since the A's acquired him in a trade from the Cubs on July 5, Hammel is 1-5 with a 6.75 ERA. His most recent outing was a debacle in Atlanta on Aug. 15, when he gave up five runs and three home runs in three innings. With two off-days last week, the A's skipped Hammel's turn in the rotation in order to put their best foot forward in the weekend series against the Angels.
The additional time has allowed Hammel to throw what Melvin characterized as "aggressive" side sessions, working on mechanics with a focus on fastball command and downward plane.
"I'm usually a guy that establishes fastball and then pitches off that," said Hammel, "so I've been throwing a lot of fastballs, just trying to get comfortable over the mound again instead of trying to do too much. Instead of being a thrower, I'm trying to get back to pitching."
The Astros will counter with ace Dallas Keuchel, who took a tough-luck loss in his last start against the Yankees. The lefty threw his fifth complete game of the season but was outdueled by Brandon McCarthy, who shut the Astros out.
"I feel like I pitched just as good as McCarthy, but he was better today," Keuchel conceded after the loss.
Keuchel ranks among AL lefty leaders in innings (third), WHIP (fifth), wins (sixth) and strikeouts (seventh). The Astros are 12-12 in his 24 starts.
A's: Soto expected to start at catcher
After being acquired from the Rangers on Sunday, Geovany Soto is slated to make his first start at catcher for the Athletics on Tuesday.
"It's been a little crazy," said Soto," but I'm looking forward to the opportunity and I'm really glad to be here. I was surprised, but really happy."
The 31-year-old Soto has only appeared in 10 games this season because of multiple injuries, notably a torn meniscus in his right knee that required surgery. He's 9-for-38 with one home run in his limited time at the plate this season, and a .248 career hitter with 92 homers in 666 games with the Cubs and Rangers.
Astros: Porter happy with improvements against A's
A year after finishing 4-15 against their divisional foes in Oakland, the Astros are 5-9 so far against the A's this season. Though the record still isn't outstanding, manager Bo Porter said he's happy with his club's efforts against Oakland, which holds one of baseball's best records.
"Baseball is about timing," Porter said. "At the times of the year in which we played them last year, we did not play good baseball. When you don't play good baseball, whether it's against the Oakland A's, Atlanta Braves or Detroit Tigers, you're probably going to struggle. I think we've played some of our best baseball against them this year."
• Heading into Monday's game, the A's and Astros were tied for third in the AL in runs scored since the All-Star break with 153. The tie was broken with Oakland's 8-2 win on Monday.
• Keuchel's five complete games are the most by an Astros pitcher since Mike Hampton had seven in 1997.
Caitlin Swieca is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.