Oakland seeks a sixth consecutive win as it visits Lincecum and the Giants on Wednesday night.
The A's (30-23) began the season winning 12 of their first 16 before an 8-18 slide dropped the defending AL West champions below .500. They've been on a tear lately, though, beating San Francisco 6-3 on Tuesday for their 10th victory in 11 tries.
Derek Norris hit a two-run homer while Adam Rosales added a solo shot to snap a 0-for-24 slump. Oakland has averaged 6.6 runs during its five-game winning streak.
''We're doing a lot of things right,'' Norris said. ''We're keeping it simple.''
The Athletics' pitching staff has posted a solid 2.39 ERA over its last 11 contests, far better than how Lincecum has thrown lately.
Lincecum's inconsistency over the past two seasons remains extremely puzzling given the past success of the two-time Cy Young Award winner. He had a career-worst 5.18 ERA in 2012 and is just 3-4 with a 4.75 ERA this season.
Each of his 2013 wins have come when he didn't allow an earned run, though he's followed up each by struggling in multiple outings.
After giving up two hits in seven scoreless innings of a 5-1 win over Atlanta on May 12, Lincecum allowed six runs in five innings of a 10-2 defeat at Colorado on May 18 before Friday's 5-0 loss to the Rockies in which he yielded four runs in seven innings.
''I just have to stop making mistakes up in the zone," Lincecum said. ''If I miss with my spots they have to be down or away. But things are right in the middle of the plate, hanging sliders, fastballs that aren't supposed to be where they are.''
The right-hander also hasn't been able to match his earlier success against the A's recently. Lincecum went 5-0 with a 1.17 ERA with two shutouts and another complete game in his first six starts versus Oakland, but he's 0-2 with a 5.06 ERA in the last three.
The Giants (28-24) have totaled five runs while losing the last three meetings with the A's, and they've scored fewer than four runs in each defeat while dropping four of their last six overall.
Hunter Pence had an RBI single in the first inning then added a solo homer in the ninth Tuesday. Buster Posey went hitless and is 0 for 7 in the first two games of this series after hitting .421 during a 10-game hitting streak.
Posey is hitting .167 in his last six games versus Oakland, which will send Tommy Milone to the mound.
Milone (4-5, 3.80) has been up and down as well. He ended a five-start skid by giving up one run in six innings of a 2-1 win over Kansas City on May 18, but he allowed five runs - all in the fifth - in seven innings before Oakland rallied to beat Houston 6-5 on Friday.
"It's a little unlike him because he usually can stem the tide and keep from having the big inning like that," manager Bob Melvin said.
The left-hander has never faced the Giants.