Harden (5-0, 2.15 ERA) is 2-0 while allowing one run and eight hits in 19 2-3 innings over his last three starts. That outstanding stretch has him in position to win a sixth consecutive decision for the first time since he did it over three seasons from Aug. 19, 2005-April 4, 2007, as shoulder injuries limited him to 14 games - 11 starts - in that span.

This season appeared headed in the same direction, as the right-hander landed on the disabled list from April 3-May 11 with a right shoulder strain. He's responded by throwing at least six innings in seven of his nine outings since being activated.

Harden is looking to become the first pitcher for Oakland (45-37) to open a season 6-0 since Dave Stewart accomplished the feat in 1990.

"When he's on, he's almost unhittable," A's manager Bob Geren told the team's official Web site.

Harden was outstanding Thursday, striking out a career-high 11 while allowing two hits and a walk in eight innings of a 5-0 victory over Philadelphia.

"I've had games where I've felt better," Harden said. "In the past I've always had that one inning when I'd lose command suddenly. I want to get away from that. I was able to locate pitches and I felt good."

Harden will try to help second-place Oakland further close the gap on the AL West-leading Angels (49-34). The A's pulled within 3 1/2 games by winning Monday's series opener 6-1 behind rookie Greg Smith, who allowed four hits in his first complete-game victory.

Harden is 5-3 with a 3.99 ERA in 13 games - 12 starts - against Los Angeles. He gave up three runs and struck out nine in six innings of a 7-3, 12-inning victory over the Angels on June 8.

The A's will try to build on their improved offensive performance from Monday. They produced 13 hits after totaling 11 with one run over the previous two games - both losses. They're hitting .309 with four homers and 36 runs in five games this year at Angel Stadium, winning three.

The Angels, losers of four of their last five, hope Ervin Santana (9-3, 3.32) can overcome his control issues to continue his dominance of Oakland.

The right-hander is 8-1 with a 1.38 ERA in 12 games - 11 starts - against Oakland, including 1-0 in two outings this season while allowing two earned runs in 13 innings. He's gone 21 consecutive innings without giving up an earned run to the A's in Anaheim.

Santana, though, is coming off a shaky outing. He allowed four runs and a season-high five walks, including one with the bases loaded, in six innings of a 5-4 loss at Washington on Wednesday. Santana struck out eight and did not get a decision.

"He had really good stuff, and those guys laid off some pitches," Angels manager Mike Scioscia told the team's official Web site. "Ervin threw the ball well."

Los Angeles hoped Vladimir Guerrero can find his rhythm after going 1-for-11 in the last three games. That stretch has followed a 16-game hitting streak, during which he batted .426 (26-for-61) with six homers and 13 RBIs.

The right fielder has gone 5-for-24 (.208) with two homers off Harden.