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Mired in a three-game losing streak only four games into the season, the Arizona Diamondbacks are already in search of answers.

Despite a late glimmer from their hitters, Diamondbacks relievers couldn't get the done Tuesday in a 6-5 loss to the Chicago Cubs.

Bases-loaded singles by Gerardo Parra and Willie Bloomquist shifted momentum to Arizona in the seventh inning and made it 4-all. But the bullpen gave it right back in the bottom of the inning.

Sam Demel (1-1) allowed an RBI double to Marlon Byrd, and Joe Paterson forced in another run with a bases-loaded walk to Tyler Colvin.

Arizona scored again in the ninth, but left the tying run on second as the game ended.

"It was great to see us fight back, but we're here to fight back and win," Diamondbacks manager Kirk Gibson said. "There's no consolation. The object is to win the game, we have to execute better."

Arizona starter Barry Enright allowed four runs on seven hits over six innings. Though he was hit hard in the first few innings, Enright settled down to retire 10 of the last 11 batters he faced.

"I was a little more aggressive toward the end of the game," the Arizona right-hander said. "I came out a little tentative, standing up pretty straight and not finishing."

Byrd, who had three hits and scored a run, helped the Cubs beat Arizona for the seventh straight time, dating to last April 30.

Chicago right-hander Andrew Cashner left after 5 1-3 innings in his first career start because of tightness in his right shoulder. He gave up one run on two hits, walked one and struck out two. Cashner made 53 relief appearances in 2010.

"He was great all game and threw the ball extremely well and the last few pitches before we got him out of there he felt a little tightness and that's all I needed to hear," Cubs manager Mike Quade said. "Up to that point, it was a real impressive outing."

Quade said he was being cautious with Cashner, though the righty will likely have an MRI done on his shoulder.

James Russell (1-0) worked 1 2-3 innings of relief for the win. Marshall gave up a run in the ninth for his first save.

The Cubs opened a 2-0 lead in the second, scoring on a throwing error and Starlin Castro's RBI double.

After Castro's hit, Cashner advanced Darwin Barney and Koyie Hill to second and third with a sacrifice and, the next batter, Kosuke Fukudome, walked to load the bases.

But as Fukudome started for first, Diamondbacks catcher Miguel Montero's quick throw to second to catch Hill skipped into center scoring Barney. Hill then came home on Castro's double to center, but Fukadome was caught at the plate on a relay from Chris Young to Montero.

Arizona third baseman Ryan Roberts cut the deficit in half with a leadoff homer in the third.

Chicago replied in bottom of the third as Colvin broke out of a 1-for-9 slump with a homer off Barry Enright to make it 4-1.

Parra had a run-scoring single in the seventh off Marcos Mateo. Bloomquist drove in two runs with a hit off Russell to tie it.

Arizona scored once in the ninth as Roberts came home on Xavier Nady's grounder to Marshall, the Cubs' fifth pitcher. Marshall struck out Bloomquist to end it.

NOTES: It's not quite a Wrigley Field version of Alfred Hitchcock's classic "The Birds," but the flock of seagulls swooping through the park on Monday definitely had manager Mike Quade concerned. "What triggers it?" he said prior to Tuesday's game. "They were here in the third inning yesterday. And then you think, 'OK, it's all the food laying around.' Maybe if I get my (Rottweiler) here, maybe we can clean it up a little." ... Colvin started at first base and batted fifth in place of Carlos Pena, who is day to day with a sprained right thumb. ... Cubs relievers Carlos Marmol and Kerry Wood had the day off after making three straight appearances. .... Following Wednesday's series finale, the Diamondbacks return to Phoenix for Friday's home season opener against the Reds at Chase Field.