He's been even better overall of late for the Kansas City Royals.
Looking to continue his success against the A's, Shields tries to win his third straight start and help the Royals take this four-game home set between division leaders Thursday.
Shields (11-6, 3.25 ERA) allowed a pair of home runs to Josh Reddick and two others hits in eight innings of a 4-2 victory at Oakland on Aug. 3. The right-hander has yielded four runs over 25 innings to win two of his last three against the major league-leading A's (73-47) - all on the road.
He followed that outing by tossing a four-hitter in a 5-0 home win over San Francisco on Saturday.
''He's got good stuff,'' Giants catcher Buster Posey said. ''That's about it. He's been good for a while.''
Shields is 3-2 with a 1.63 ERA in seven outings since an eight-start stretch during which he went 2-1, but had a 5.66 ERA.
"Just staying consistent and just being a grinder really," he told MLB's official website of his recent success.
Shields could have a tough time topping Jason Vargas' three-hitter in Wednesday's 3-0 victory. Omar Infante hit a two-run homer as the AL Central-leading Royals (65-54) bounced back after their eight-game winning streak ended with Tuesday's 11-3 defeat.
''That's what we want to do if we want to keep playing,'' Vargas said.
A winner in 17 of 21, Kansas City is 4-2 against the A's this season.
Oakland has totaled three runs in its three losses over the last four games. The A's pounded out a season-high 20 hits Tuesday, but have 12 in the other three over that span.
Two of the six times Oakland has been shut out this season came against the Royals.
''You just have to keep after it,'' A's manager Bob Melvin said. ''At times, you're going to get well-pitched games against you and today was one of those. I don't think our approach was any worse (Wednesday) than it was (Tuesday). It was counteracted by a guy that pitched a great game.''
For the second straight start Oakland's Jeff Samardzija (3-1, 3.08) allowed two runs, the most recent coming Saturday, along with seven hits over six innings of a 9-4 victory over Minnesota.
The right-hander's only other appearance against the Royals came in relief for the Chicago Cubs in 2011.
Nori Aoki has faced Samardzija the most of any Royal, going 7 for 16 with a double and two triples against him.
Aoki is batting .343 with 13 runs scored in his last 20 games. He has hit .387 with six runs in nine career contests against the A's.
Oakland's Josh Donaldson is batting .400 during a 10-game hitting streak, and is 2 for 6 with a home run versus Shields.
Three of Reddick's five hits in 19 at-bats against Shields have left the park.
Despite a three-hit game Tuesday, Reddick is 5 for 26 in his last seven contests.