Will a pair of aces fold?

From the day Joe Torre was introduced as manager of the Dodgers, he said they would go as far as their pitching would take them. With his team preparing itself for its final three games against the only team it trails in the NL West, he issued another challenge to his pitchers.

“You really don’t have to beat their pitchers,” Torre said, “but you have to match them.”

Starting for the Arizona Diamondbacks tonight at Dodger Stadium will be Dan Haren. On the mound Saturday will be Brandon Webb, who will be followed Sunday by Randy Johnson.

But entering this three-game series, All-Stars Haren (14-7) and Webb (19-6) could be more concerned about matching the Dodgers’ Derek Lowe and Chad Billingsley instead of the other way around.

Haren and Webb haven’t looked like themselves recently, including in Arizona last weekend when the Dodgers beat them. The downturn in form could be problematic for a team that ranked 19th in the majors in runs scored through Wednesday.

“We’ve got a month left and hopefully, it’s a new month,” Haren told reporters Wednesday. “The team relies on us.”

The Dodgers ended a season-long eight-game losing streak six days ago by scoring five runs in six innings against Haren. A day later, they pounded Webb for eight runs, six of them earned, in 3 1/3 innings.

“You have to give the guys credit for finding a way to beat those two guys,” said Lowe, who beat Webb by tossing six scoreless innings.

Torre said he felt the victories had psychological benefits.

“I’m glad we battled them,” Torre said. “You certainly don’t anticipate beating pitching like that.”

The Dodgers took that momentum back to Dodger Stadium, where they swept the San Diego Padres in three games and closed the gap with the Diamondbacks to 1 1/2 games.

Haren is 3-2 over his last six starts but has a 5.63 earned-run average over that span. Those opponents hit .337 against the right-hander, who posted a 1.95 ERA in July.

Webb went into his last two starts in position to become the first pitcher in the majors to win 20 games but pitched only a combined eight innings in those games and gave up 14 runs.

Webb’s patented sinker didn’t sink when he faced the Dodgers, raising suspicions in the victorious clubhouse that the former Cy Young Award winner was affected by a line drive that bruised his chest three starts ago in San Diego.

Webb denied that.

“I don’t think so,” he told reporters. “I think it’s more mechanical with the arm slot. I’m trying to guide it in there. . . . I know what I’m doing wrong, so hopefully I’ll be able to correct it in another game.”

If he can, it could be trouble for the Dodgers, who were held to two runs in 16 innings the first two times they faced him this season.

Haren admitted that fatigue could be an issue. Webb ranks third in the NL in innings pitched with 192. Haren is seventh with 186.

“If you ask any pitcher in the league at this point in the year with the innings we’ve thrown, everybody’s going to say they’re a little tired,” Haren said. “But that’s no excuse. There are only a handful of guys who throw 200 innings every year and when you get to that point, you’ve got to push through it.”

The way the schedules of the Dodgers and Diamondbacks compare, Haren and Webb might have to add to their win totals for their team to reach the postseason.

The Dodgers don’t face another team with a record over .500 and have six games remaining against last-place San Diego. The Diamondbacks’ schedule includes a four-game series in St. Louis from Sept. 22-25.

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dylan.hernandez@latimes.com

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This weekend at Dodger Stadium

ARIZONA VS. DODGERS

Tonight: 7, FSN Prime Ticket

Haren (14-7) vs. Lowe (11-11)

Saturday: 12:45, Ch. 11

Webb (19-6) vs. Billingsley (13-10)

Sunday: 1, FSN Prime Ticket

Johnson (10-9) vs. Kershaw (3-5)