Oakland acquired Cust from the San Diego Padres on May 3 and promoted him from Triple-A Sacramento when Mike Piazza went on the disabled list last Friday. He is hitting .316 (6-for-19) with four homers and nine RBI in five games with the A's.
"I've seen him since 1999 and I've always respected the way he swings the bat," A's manager Bob Geren said. "The offense was sputtering early a bit but now the power numbers are coming."
Cust hit a tiebreaking two-run homer off Sabathia in the seventh and a two-run single off Roberto Hernandez in the eighth. Cust, who went 2-for-4 against the Indians, homered twice in Oakland's 17-3 victory over Kansas City on Thursday.
"You put together pretty good numbers in the minors but sometimes you think scouts have seen you so much, they're not telling anyone," Cust said. "I sat in Triple-A for seven years but (family) kept telling me to keep at it."
Joe Blanton (4-1) took a shutout into the sixth inning, and won consecutive starts for the first time this season.
"My fastball and sinker have been my best pitches and I've been able to locate them," Blanton said. "That's allowed me to get ahead of hitters. I feel confident going at hitters."
Sabathia (5-1) allowed six runs and nine hits in 6 2/3 innings. He struck out five and walked one as the Indians lost their third straight.
Dan Johnson extended his hitting streak to 11 games with an infield single in the second inning for Oakland, which won for the fourth time in five games. Johnson went 3-for-4 and scored a run.
Sabathia, a native of nearby Vallejo, dropped to 1-5 with a 6.60 ERA in 11 career starts against the A's. His only win against them came in July 2003.
"It's me trying too hard," Sabathia said. "Any situation anywhere else and I can stop the bleeding. I want to do well in front of my family so I try too hard."
Ryan Garko had three hits, including a home run, and drove in two runs for the Indians.
"Garko had a real good night and a couple of other guys are going OK," Cleveland manager Eric Wedge said. "We need to get everybody else going. That's where we're at right now. C.C. threw a great ballgame. He left one over for Cust and it dominoed on him from there. That doesn't take away from how he pitched."
Blanton retired 15 of the first 16 batters he faced before Garko led off the sixth with his fourth homer. Blanton went seven-plus innings, allowing two runs and five hits. He struck out four and did not walk a batter.
Bobby Crosby's fifth-inning home run was the only dent against Sabathia until the A's scored five runs with two outs in the seventh.
Cust's two-run homer on a 2-1 pitch from Sabathia made it 3-1. Sabathia walked Mark Ellis and then gave up consecutive hits to Jason Kendall, Shannon Stewart (a two-run double), and Nick Swisher (RBI single) before Thomas Mastny replaced him and gave up a single to Eric Chavez before getting out of the inning.
- A's RHP Rich Harden threw on the side before the game as he attempts to come back from a strained right shoulder.
- Oakland optioned OF Danny Putnam to Triple-A Sacramento to make room for Milton Bradley, who was reinstated from the 15-day disabled list.
- A's OF Chris Snelling missed the game with a knee injury.
- The Indians had won eight of their previous 11 series-opening games.
- The A's drew 20,393 fans while across the plaza the Warriors' playoff game drew 20,655.
- The Indians have lost four straight to Oakland.