PHOENIX -- You can take the Diamondbacks out of the National League West. But you can't take the NL best out of the Diamondbacks.

And now one of their ace pitchers is starting to feel healthy?

Seven nearly perfect innings out-weighed one imperfect one Monday night for Dan Haren, who made sure the Diamondbacks continued running a fever by throttling the Astros, 5-3.

After helping Arizona improve its record to 19-7, Haren delivered even worse news to the rest of the division, which now lags 6 1/2 games behind. Coming out of a 17-5 stretch of intradivisional games, the D-backs didn't break stride.

"That was, absolutely, without a doubt, the best I've felt. I caught a bit of the flu going around early on, and I'm just now getting back to my usual routine," said Haren, whose routine Monday night was pretty extraordinary.

All concurred that the right-hander flashed his top stuff of the young season, which made him virtually unhittable for long stretches.

Haren (4-1) shined for 7 2/3 innings, allowing a total of seven baserunners, five of them in the fifth inning, as Arizona ran its Majors-best home record to 10-2 in front of 19,868 in Chase Field. He walked one, struck out five and threw 71 of his 103 pitches in the strike zone.

"His velocity picked up. His curveball was sharp," said manager Bob Melvin.

"This was my first start after feeling I'm finally getting back to normal," Haren said. "And I felt real good out there. The game was going real quick, and I liked that."

After sailing through the first four innings -- retiring all 12 men he faced -- Haren sweated through the fifth. Following a leadoff walk of Lance Berkman, Carlos Lee ripped a double to left-center for Houston's first hit. The two took turns scoring on Hunter Pence's infield grounder and Mark Loretta's single, but Haren slammed the door shut with the bases loaded and one out, preserving a 4-2 lead.

"I would've liked to avoid that 30-pitch inning," Haren said, "so the results may not have been the best, but I felt like I was throwing my best."

"That's the stuff we saw in Spring Training," said Haren's catcher, Chris Snyder. "He hadn't been feeling completely in sync. But tonight he said he felt good, and it showed."

Haren carried the game down to where he needed only a minimal assist from an overworked bullpen. Chad Qualls came on to pull the plug on Houston's last rally of the evening by getting the last out in the eighth, then Brandon Lyon worked a perfect ninth for his seventh straight save, and eighth overall.

The Diamondbacks had aired out a budding pitchers' duel with a three-run strike against Chris Sampson in the fourth, when Mark Reynolds doubled for two runs and scored on Chris Snyder's single to make it 4-0.

Haren had accounted for his own first run, doubling over Pence's head in right with one out in the third to score Stephen Drew, who had led off the inning with a double.

That blow was the fifth extra-base hit by Arizona pitchers and resulted in the eighth RBI by a staff which clearly believes in helping itself. These pitchers would be batting seventh for Tony La Russa in St. Louis.

"If you can do that in the pitcher's spot," Melvin said, "it's big in the National League."

Conor Jackson arranged for an insurance run in the fifth with a run-scoring single that gave the D-backs a 5-2 lead and chased Sampson (1-3).

Haren was working on another string of 10 consecutive outs before Michael Bourn doubled with two outs in the seventh. Miguel Tejada followed with another two-bagger to nearly the same spot in left-center, trimming the lead to 5-3 and excusing Haren in favor of Qualls.

Qualls fanned the Astros' cleanup hitter, Berkman, to maintain the two-run lead.

Once Lyon was finished slamming another door, the D-backs again had to don blinders to avoid being impressed by their 19 wins.

"You can't help looking at the start we've had," Melvin said "but we try to keep it simple. We play day-to-day and not get caught up in records and such. It's been a good recipe for us."

Good may not begin to describe it. On another night of clutch hitting, tenacious pitching and acrobatic defense, the Diamondbacks' biggest disappointment was the lack of an icing hit.

With electric pitching prospect Max Scherzer warming up in the bullpen for his Major League debut, Snyder bounced into a bases-loaded double play to end the eighth and keep the game within the veteran Lyon's range.

"If Snyder hits one in the gap there, Scherzer is in the game," acknowledged Melvin, who looked forward to unwrapping Scherzer's young arm, and these days must look really hard to find something to rue.