PHOENIX -- There was no demonstration of anger from Rockies outfielder Carlos Gonzalez. He simply tossed his bat aside, pulled off his shin guard and walked to the outfield.

Gonzalez struck out with one on to end the eighth inning -- the Rockies' only threat against the D-backs and pitcher Joe Saunders -- in Colorado's 3-1 loss at Chase Field.

Make no mistake. Gonzalez, who doubled earlier in the game, was frustrated. There's no other way to feel for him or the Rockies, who fell to 2 1/2 games behind the National League West-leading Giants and two games behind the second-place Padres.

"We need to beat these guys," Gonzalez said. "They're out already and we want to make it to the playoffs. We've got to be able to win this game."

Both teams ahead of the Rockies won in shutout fashion Tuesday. The Giants, behind pitcher Matt Cain, earned their eighth 1-0 decision of the season, over the Cubs. The Padres' Clayton Richard earned his first shutout with the club, 6-0 over the Dodgers.

Meanwhile, the Rockies were nearly shutout victims.

"We've got two more games of this series and a huge series [with the Giants at home] over the weekend," said Rockies manager Jim Tracy, who has ace Ubaldo Jimenez (19-6) pitching Wednesday night against the D-backs. "We need to take care of tomorrow first."

But the Rockies have had trouble winning at Chase Field, where they're 2-5 this season. Saunders (9-16) lasted just 2 1/3 innings and gave up seven runs, four earned, in a Sept. 10 loss to the Rockies at Coors. But there was no beating him Tuesday night.

"We've seen Joe like that more in Anaheim when we faced him than we have here since he's become a Diamondback," Tracy said. "To his credit, he was very effective."

This time, Saunders struck out seven and gave up six hits in eight efficient innings. The Rockies had more than one man on base just once. Finally in the eighth, Miguel Olivo led off with a double and scored on pinch-hitter Ryan Spilborghs' single.

Dexter Fowler launched a fly to deep right-center that landed in the glove of the D-backs' Chris Young. However, Saunders struck out Jonathan Herrera, who extended the at-bat to 10 pitches but looked at strike three, and Gonzalez went down on a full-count curveball. Gonzalez's double in the fourth came on a full-count fastball.

"That's when I want to hit the double," said Gonzalez, who struck out twice against Saunders. "I don't want to hit a double with no one on, but he pitched me backwards. He pitched well."

The top two hitters in the Rockies' order, Fowler and Herrera, went a combined 1-for-8, meaning Gonzalez and Troy Tulowitzki, who has 14 home runs and 34 RBIs this month, had little opportunity to drive in runs. Tulowitkzi had one hit and Saunders hit him after Gonzalez's double -- plate umpire Doug Eddings eventually issued warnings to both teams after Rockies pitcher Jorge De La Rosa nearly hit Stephen Drew in the fifth -- but otherwise, little happened for the Rockies.

De La Rosa (8-5), who had won his previous four decisions, went seven innings, struck out five and gave up six hits. However, three came with two out in the third, and they cost him the game.

Lefty hitters came into the game with a .190 average and two home runs against De La Rosa. But leadoff man Stephen Drew doubled and singled against him. After his third-inning single, Drew scored on Ryan Roberts' double. Then Kelly Johnson launched just the third homer from the left side off De La Rosa, on a first-pitch fastball for a 3-0 lead.

"For whatever reason, I just wanted to go up and look for that first-pitch fastball and try not to miss it if I got a good one and, fortunately, I hit it hard," said Johnson, who has 23 home runs this season.

Juan Gutierrez struck out two in the ninth while earning his 10th save.