The Rays got the timely hits, and a little home-field advantage, to back rookie starter Jeff Niemann, who hurled his second career shutout in a 6-0 win. Niemann outpitched fellow rookie Vin Mazzaro, who lost his fifth straight decision.
"We stayed away from the big inning, as far as our pitching went," A's manager Bob Geren said. "We just didn't score."
Niemann, who is 6-1 with a 2.54 ERA in his past 10 starts, was dominant with his sharp overhand curveball and a fastball veering in the low 90s. The curveball nullified Oakland's left-handed hitters, who went a combined 3-for-14 against him.
The A's offense entered the game batting .296 over the past 11 games. On Friday, though, it looked a lot more like the unit that ranks last in the American League in several categories.
"[Niemann] pitched well," A's third baseman Adam Kennedy said. "He's a big guy, so he has a good angle on us. For me, I don't take advantage of squaring the fastball up and the curveballs pretty good."
It was a sloppy performance by Oakland, losers of five of the last seven. An error by shortstop Orlando Cabrera on a pickoff attempt at second base allowed a run to score in the first inning. A wild pitch by reliever Santiago Casilla resulted in a run in the sixth.
And the first-inning foul popup by Upton, though not necessarily too costly, was nonetheless embarrassing. Catcher Kurt Suzuki, first baseman Jason Giambi and Mazzaro each went after it, but the ball fell in.
"I didn't see it at all," Mazzaro said. "I saw it go up and then I saw it come back down."
"I think all three of us didn't see it," Suzuki said. "That's a tough play. Nobody wants to call it because you can't really see it. It was a tough one."
Upton later reached on a double and scored on a groundout by Carl Crawford. In the fourth, Carlos Pena hit a solo home run, his AL-leading 24th of the season. Evan Longoria added his 17th homer in the seventh.
Mazzaro fell to 2-5 after winning his first two starts, the longest losing streak by an A's pitcher all year. Against the Rays, Geren thought the rookie gave a decent performance, but the offense didn't back him up.
Geren added that he expects the 22-year-old Mazzar to have a strong second half, despite what he's shown recently. He gave up five runs on 10 hits in six innings to Cleveland on Saturday.
"It's tough," Mazzaro said. "You've got to just keep pitching, try not to worry about it. You're going to hit a stage where things aren't going your way. It's just how you recover and battle back."
Tampa Bay, which is second in the Major Leagues in runs scored, walks, on-base percentage and run differential, scattered its runs across the board. But it was enough to sink Oakland, which had zero extra base hits, left nine runners on base and went 0-for-6 with runners in scoring position.
Oakland came in hoping to end the first half on a positive note. It has been in last place in the AL West since early May, the latest it has been in that position since 1998.
But from the very first batter, things didn't seem to go the way the A's would've liked. And with the bats silent, the night didn't get any easier.
"He's not unhittable," Geren said of Niemann. "But in a couple outings against us we didn't do much. Tonight was no exception. Getting shut out in this ballpark -- we've got to score some runs."