LOS ANGELES -- It's a showdown in Chavez Ravine this weekend: Diamondbacks-Dodgers for the last time during the regular season. Sellout crowds at Dodger Stadium. First place in the National League West on the line with little more than three weeks remaining.

"At this point in time, we're about as ready as we could ever be to play this series," Dodgers manager Joe Torre said on Thursday.

"They're all big series, but this one is as important as any all year," said D-backs manager Bob Melvin. "They are right behind us going into L.A. We are in September and it's the last time we play them, so it's going to be a significant series."

The Diamondbacks hold a scant 1 1/2-game lead over the Dodgers heading into the series and Melvin has manipulated his pitching rotation so his big three go in this order: Dan Haren, Brandon Webb and Randy Johnson. They'll face Derek Lowe, Chad Billingsley and rookie Clayton Kershaw.

The D-backs haven't gotten much from their top arms the last few times around the rotation. After they defeated the Dodgers at Chase Field last Friday night to take a 4 1/2-game lead, the world seemed rosy with Haren and Webb starting the next two games.

Both pitchers were creamed as the Dodgers won the crucial pair.

Webb will be making his third stab at becoming the first NL pitcher since 2005 to amass 20 wins during a single season. Haren is on try No. 3 at notching his 15th. Johnson hasn't won since Aug. 12 and is stuck on 294 career victories (10 of them this season). Nailing 300 this year now seems to be out of the question.

"We're facing the big three, and again, we beat two of them last week, but really our goal right now is to win those games," Torre said. "We don't necessarily need to beat those pitchers, but we need to really match them pitching-wise going in, and that's my goal right now, be ready to play and just make sure we don't give them any liberties."

Torre adds another subplot. He's in his first season managing the Dodgers after taking the Yankees to the playoffs 12 times in a row. Can he make it a personal 13? His old club, which has been there every year since 1995, is facing the possibility of sitting out the postseason for the first time in a completed regular season since 1993.

The Dodgers, in contrast, have only made the playoffs twice since 1996 (2004, under Jim Tracy; and 2006 under Grady Little) and have won just a single postseason game since defeating the A's in the 1988 World Series (in '04, under Tracy).

What the Dodgers do this week may go a long way to determining their fate.

"This is as big as it gets," said Russell Martin, the Dodgers' second-year catcher. "At this point in the season, it's going to be a playoff atmosphere. And I think everybody realizes that we're close, we've just got to keep pushing, keep playing hard and just keep rolling on this wave that we're on right now."

The D-backs, meanwhile, have been bending all season, but thus far, they haven't broken.

Save for four consecutive days in early April, the defending NL West champs have been in first place since Sept. 4, 2007. For them, last season was a battle to the wire with the Padres and Rockies that ended with a division title, but a sweep at the hands of Colorado in the NL Championship Series.

This year, the Dodgers have tied them (four times from Aug. 13-17), but the D-backs were able to regain the lead. Arizona's biggest bulge was last week's 4 1/2-game advantage, but the Dodgers came rumbling back.

At the All-Star break, the D-backs led the Dodgers by one game. Since then, the Dodgers added Manny Ramirez and Casey Blake. The D-backs countered by adding Adam Dunn and David Eckstein, among others.

Take a look at the standings. Not much has changed.

"The further into September you get, the more the pressure will build up," said Dunn, the former Red who has never played in the postseason. "When we play the Dodgers, it's like a playoff atmosphere. It's fun. I love it. This is what baseball's supposed to be."