Arizona center fielder Chris Young can't come up with an eighth-inning double off the wall by Ronnie Paulino Wednesday in the Pirates' 5-1 victory.

PITTSBURGH — This wasn't supposed to be happening to these Arizona Diamondbacks, not now and especially not in this place.

Adam LaRoche drove in three runs with a pair of doubles and Matt Morris pitched effectively over seven innings as the Pirates beat Arizona for the second night in a row, a 5-1 decision Wednesday that further tightened the NL West race.

The Diamondbacks, in position when the series started to clinch the division before going to Colorado to finish the season, have dropped three in a row since winning five of six. Their lead was trimmed to a game over San Diego, which beat San Francisco 11-3, and their magic number for clinching the division remained at four. Colorado beat Los Angeles 2-0 to move within two games of Arizona.

"It definitely puts some pressure on us, but you can't push the panic button — we're still in a good spot," Conor Jackson said. "We need to come out and play like we have the last two months. This is kind of uncharacteristic for our ballclub, but we're going to bounce back. We've got four games to do some damage."

Especially today, when they throw staff ace Brandon Webb (17-10), last year's NL Cy Young Award winner, against the Pirates' John Van Benschoten (0-6, 9.73 ERA), whose only major league win came in 2004.

For two nights, the Pirates haven't resembled the team that had lost nine in a row entering the series and has long since been assured of a 15th consecutive losing season, one off the major league record.

"They're not going to throw a party over there, not while they're here," manager Jim Tracy said.

Pirates rookie Nyjer Morgan tormented Arizona again by reaching base three times, getting a pair of hits and making an excellent catch that possibly prevented the Diamondbacks from taking a lead in the second inning. Xavier Nady added a solo homer against Livan Hernandez (11-11), who struggled yet again in PNC Park by allowing 10 hits and four runs over four-plus innings.

"People think we're going to be a pushover," Morgan said. "But everybody here comes to play everyday."