OAKLAND -- The A's have been waiting for someone or something to ignite their slumping offense.

That someone turned out to be Jack Cust, and that something was a grand slam Thursday against the Texas Rangers that lifted the A's to a 9-4 victory and rookie Trevor Cahill to his first Major League win.

Cust's slam off Brandon McCarthy was the big blow in a five-run fourth inning, giving the A's a 5-0 lead. Matt Holliday followed with a three-run shot off reliever Kris Benson in the fifth.

This was exactly the type of explosive offense the A's expected to have after an offseason in which they added Holliday and Jason Giambi to the heart of their order.

But entering Thursday's game, the A's ranked last in the American League in hitting (.234), runs (103), slugging percentage (.329), on-base percentage (.310) and extra-base hits (56).

"It feels good," Cust said. "In that situation, bases loaded, nobody out, there's not a lot of pressure on the hitter. You've just got to basically hit a ball in the air. That's what I was trying to do. I wasn't trying to hit a home run.

"When it happens, you can feel it in the dugout, the excitement, the energy. It's something we haven't felt in a while. It definitely felt good. Hopefully we can take that energy into the next series and continue hitting the ball like we did today."

A's manager Bob Geren shuffled his batting order Thursday, hoping to generate more offense. He moved Orlando Cabrera up one spot from second to first and dropped Ryan Sweeney from leadoff to sixth. Kurt Suzuki, typically a sixth- or seventh-hole hitter, hit second against the Rangers.

Yet through three innings, it was the same old slumbering A's, as Cahill and McCarthy were locked in a scoreless duel. But in the bottom of the fourth, Suzuki lined a leadoff single to left and McCarthy issued back-to-back walks to Giambi and Holliday, loading the bases and bringing Cust to the plate.

Cust launched McCarthy's 0-1, belt-high fastball deep into the right-field stands, putting the A's ahead, 4-0. It was Cust's second career grand slam, following his slam on Aug. 10, 2007, at Detroit. The A's made it 5-0 when Bobby Crosby singled, stole second and scored on Jack Hannahan's double.

"We needed something to jumpstart us," said Crosby, who went 3-for-4 with two doubles. "It was good to get a lead. When Jack hit that grand slam, it kind of took the pressure off everyone a little bit. We've been struggling to score runs. ... I think guys kind of just maybe relaxed a little bit. I think guys have been pressing."

Holliday certainly looked relaxed when he sent a three-run rocket into the left-field seats in the fifth. Once again, Suzuki led off with a single to left. Giambi followed with a single, setting the stage for Holliday.

Holliday didn't hit a single home run in Spring Training or in the A's first 17 regular-season games. Now he has four homers in his past 12 games.

"I feel like it's coming along pretty good," Holliday said of his swing. "The last couple days I felt pretty good."

Holliday still has a .233 batting average to deal with, but he's just one of many A's sluggers trying to dig his way out of deep holes. Thursday's 12-hit outburst might have been the start of a team-wide turnaround.

"I hope so," Holliday said. "It doesn't always work that way, but I definitely think that confidence is an important part of this game, and when ... five or six guys have good at-bats, confidence is high for all those guys, and it carries over."

If it does, then watch out, Suzuki warned.

"When it comes, it's going to be scary," Suzuki said. "Guys like Matt, Jason, they're going to hit. There's no question about it. When we do get those guys going and we get going as a team, we're going to be dangerous."

The way Cahill pitched, he didn't need all those runs, but he wasn't complaining. Cahill allowed just five hits (four doubles and one homer) and one run over seven innings, striking out four. But here's the key stat: he didn't walk a single Ranger.

"That's just one of those things that's been my weakness my whole career," Cahill said. "I just went after them today. When I did get behind, I didn't give in. ... No walks is definitely a huge step."

Cahill blanked the Rangers on three hits through the first four innings. The Rangers touched him for a run in the fifth on Chris Davis' solo shot to right, cutting the lead to 5-1.

"A great outing," Geren said. "I thought he really threw the ball well. A lot of movement, very consistent with the delivery. That's exactly what we're trying to get from him right there. He went deep into the game."

And Cust went deep into the stands with the bases loaded, giving the A's exactly what they needed.