In 18 games since returning to the leadoff spot on Sept. 5, Phillips has struggled while batting .197 with a .265 on-base percentage. He was 2-for-4 and scored the lone run in Friday's 1-0 victory over the Pirates.
"He says, 'I'm seeing the ball so well I think I can hit everything,'" Speier said. "It's a matter of just disciplining himself and staying with his strengths in the zone. I thought he was really good [Friday] night. I thought he was a lot better."
Speier expected to have Jay Bruce, Zack Cozart and Scott Rolen rest on Sunday, while Ryan Ludwick is expected to return to the lineup after not playing since Sept. 19 because of a groin injury. Ludwick pinch-hit in the eighth inning Saturday night and hit a double.
"That looks like the plan as we speak," Speier said.