PHILADELPHIA -- The images were fresh in D-backs pitcher Chad Qualls' mind after reviewing them on videotape.

A down-and-away slider to Pat Burrell. An inside fastball to Pedro Feliz.

"Nine out of 10 times, I go out there and throw to those locations, I'm going to have a 1-2-3 inning," Qualls said.

On Sunday, however, the pitches to Burrell and Feliz ended up sailing into the stands at Citizens Bank Park, as Qualls surrendered four runs in the eighth inning of the D-backs' 6-3 loss to the Phillies.

Qualls took the ball in the eighth from starter Brandon Webb with the game tied at 2. Qualls allowed singles to Chase Utley and Ryan Howard before Burrell blasted a three-run homer, making it 5-2. Two batters later, Feliz added to the Phils' lead with a solo blast.

"That's just the frustrating part about this game," Qualls said. "I thought I turned in a good effort. All I can do is keep throwing my stuff."

The D-backs held a 2-0 lead through four innings, aided by Chad Tracy's solo home run in the second. Tracy, who also had a base hit in the sixth, is hitting .476 (10-for-21) in the past four games.

Arizona missed an opportunity for more runs in the seventh. With runners on first and second and one out, Orlando Hudson drove the ball to right field, but Geoff Jenkins couldn't make the play. Stephen Drew, the runner on second, didn't see that Jenkins couldn't make the grab and had to hold at third. Hudson was halfway to second and fell down, making him an easy second out.

"Usually, if it hits the wall, it bounces off somewhere and you get a clearer view of that," manager Bob Melvin said.

Despite the loss, the day contained several positives for Arizona. The team retained its hold on first place in the National League West, although its lead over the second-place Dodgers is shrinking.

The D-backs' hitting, also, has continued to improve. Though they entered Sunday's game with a .247 average -- 14th in the NL -- they have hit .314 (53-for-169) in their past four games.

Still, the D-backs now head into the break one game below .500, at 47-48, after starting the season 19-7. Despite turning in a quality start, Brandon Webb missed an opportunity to notch his Major League-leading 14th win.

"The break comes at a good time," Webb said. "We've been struggling for awhile. We show signs of excitement, swinging the bats. Then the next day, [we] kind of come out flat. Hopefully, we can start the second half like we started the first."