PHOENIX (AP) -- For the second weekend in a row, the Arizona Diamondbacks have a chance to take command of the NL West.

They missed an opportunity last week in Chase Field, where they beat the Los Angeles Dodgers to take a 4 1/2 game lead with aces Dan Haren and Brandon Webb pitching the next two days. The Diamondbacks dropped both those games, and now they take slim 1 1/2 game lead into the opener of a three-game series in Los Angeles on Friday night.

It's the final regular-season series between the rivals. The Diamondbacks are 8-7 against the Dodgers this year and have split six games in Chavez Ravine.

"You look at this one on the schedule and I think everybody's pretty excited about the series, and I would say including the Dodgers," Arizona manager Bob Melvin said. "It's got the makings of a playoff-type feel. Within our division, I don't think there's a more important series this year than the one that's coming up."

Haren (14-7, 3.24 ERA) will face Derek Lowe (11-11, 3.69 ERA) on Friday night. Webb (19-6, 3.19 ERA) goes against Chad Billingsley (13-10, 3.13 ERA) on Saturday night. On Sunday, Randy Johnson (10-9, 4.21 ERA) will face Clayton Kershaw (3-5, 4.50 ERA).

Haren and Webb have both struggled recently. Haren had a 5.63 ERA in August, and Webb is coming off back-to-back outings in which he has allowed six earned runs.

The defending NL West champions aren't exactly racing to the finish line. They're 71-68 overall and only 15-16 since Aug. 1.

In any other division, the Diamondbacks wouldn't have a prayer of contending. But their slump hasn't cost them much ground in the woeful NL West, where they are the only team with a winning record. The Dodgers have shaved only 1 1/2 games off the lead since Aug. 1.

The Diamondbacks have dropped seven of their last 10 games, but they hope to carry some momentum from Wednesday's dramatic 4-3 victory over the St. Louis Cardinals, which they won with two runs in the last of the ninth.

"Hopefully we'll take this into Dodger Stadium and see what happens," said Stephen Drew, who sparked the rally with a leadoff triple.

Melvin was so concerned about his team's morale that he was jotting notes on his lineup card for a postgame pep talk. He junked the talk after the Diamondbacks rallied, but he expressed caution about placing too much importance on the victory.

"I don't want to say it's a cure-all, but going to L.A. it certainly makes you feel a lot better," Melvin said.

In some ways, the game was microcosm of Arizona's season. The Diamondbacks haven't looked good for long stretches, but they've shown resilience. Despite its struggles, Arizona has managed to stay in first place since April 6, a span of 150 days.

"Obviously, our record isn't the greatest in the world," Melvin said. "Yet every time we've been pushed, we've seemed to have responded."

Indeed, when the Diamondbacks slipped into a first-place tie with the Dodgers on Aug. 13, they won three straight to regain sole possession of the lead. After Los Angeles caught them again on Aug. 17, the Diamondbacks won three more in a row, and they have been alone atop the division since.

"Whether or not it takes that to get us going at a little different level, I'm not altogether sure," Melvin said. "I would hope that's not the case. But to this point in time in the season we have been there for quite a while, and we have responded every time our backs have been pushed to the point where we could potentially give (the lead) up."

The Diamondbacks remain a relatively young team. But they say they are drawing on the experience of last season's pennant race.

"You're going to have ups, you're going to have downs," left fielder Conor Jackson said. "It's how you handle it, I think, that separates the average big leaguers from the superstars."

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