Gray and the A's go for a three-game sweep over the visiting Tampa Bay Rays on Wednesday.
Among the AL leaders in wins, Gray (12-4, 2.59 ERA) was named the league's pitcher of the month for July after going 5-0 with a 1.03 ERA. The right-hander, who also took home the award in April, became the first Oakland pitcher to win it twice in the same season since Barry Zito in 2001.
"This last month I got back to what got me here and the reasons I've been so successful and started doing those things again," Gray told MLB's official website. "Just being competitive, attacking guys and not trying to trick people, just make pitches."
Gray is looking to get back to his winning ways after taking a hard-luck loss in Friday's 1-0 defeat to Kansas City. He yielded one run and three hits over seven innings while striking out seven.
"Fastball is moving all over the place, good command of his curveball and just enough changeups to keep them off balance," manager Bob Melvin said. "You feel like if you can give him one or two runs you're going to win the game. We just didn't give him anything."
Overshadowed by fellow newcomers Jeff Samardzija and Jon Lester, Jason Hammel finally earned his first win with the A's in Tuesday's 3-0 victory. He pitched effectively into the sixth inning as Oakland (69-43) improved to 7-1 in its last eight against Tampa Bay.
The Rays (54-59), who have been limited to 14 runs during that stretch in the series, have dropped five of six overall.
"You've got to do all the little things well to beat these guys right now," manager Joe Maddon said following Monday's 3-2, 10-inning defeat. "I'm here to say we're as good as they are. I know the record doesn't reflect that, but we're as good as this team is. We've got to prove it on the field."
Jennings is hitting .167 over a nine-game stretch and Kevin Kiermaier is 2 for his last 21.
The Rays will try to get on track behind Jeremy Hellickson (0-1, 3.29). The right-hander, who debuted July 8 after undergoing offseason elbow surgery, has failed to make it through five innings in all three of his starts.
Hellickson was tagged for four runs and served up two homers over 4 2-3 innings in Friday's 5-3 defeat to the Los Angeles Angels.
"That's not going to work," Maddon said. "He has to go deeper into the games."
Hellickson threw seven innings of three-hit ball in a 1-0 win over Oakland on April 20, 2013, improving to 1-1 with a 4.00 ERA in the series.
A's shortstop Jed Lowrie missed Tuesday's win with a bruised finger, leaving his status for this game unclear. He's 0 for 9 against Hellickson since 2011.
Josh Reddick is hitting .418 with four homers and 11 runs over a 16-game stretch, raising his average 49 points to .263.
Oakland has taken five straight and 15 of 21 from the Rays at home.