Wellemeyer needed 117 pitches to navigate six innings although he posted his fourth quality start in his last five.
The Cardinals' 10th loss in 12 games dropped them to four games over .500 for the first time since April 25.
First baseman Albert Pujols, whose chances of winning the batting title are slipping away, went hitless for the third game in the last four (he had two walks) and fanned with two runners on in the seventh and the Cardinals down a run.
The Cardinals have scored only seven runs in Wellemeyer's last six starts, including being blanked three times. He is 2-4 in that stretch.
DIAMONDACKS 4, CARDINALS 2: The Cardinals' middle infielders, SS Cesar Izturis and 2B Felipe Lopez, each had three singles, but the Cardinals couldn't put the hammer down in an 11-hit offense that featured just one extra-base hit, an eighth-inning double by 3B Troy Glaus. With runners at second and third and nobody out in the eighth and the Cardinals down two runs, Glaus was doubled off second on LF Aaron Miles' soft liner to Arizona 2B David Eckstein.
NOTES AND QUOTES:
--RHP Chris Carpenter's ailing right shoulder, which underwent more tests recently, does not have a structural damage, although Carpenter will visit a specialist on Tuesday to try to determine what is causing a nerve irritation in the shoulder. Carpenter hasn't won a game in either of the last two seasons and missed most of 2007 because of an elbow-ligament problem that required surgery.
--RHP Josh Kinney, who missed most of the last two seasons because of various elbow issues, has pitched five scoreless innings, giving up only two hits and fanning six while walking no one. He threw a perfect seventh Monday.
--RF Ryan Ludwick's three straight strikeouts before he singled in the eighth inning raised his whiff total to 141 for the season.
--1B Albert Pujols is 0 for his last 11, dropping his average to .348. He's still second in the league in hitting but has fallen 16 points behind Atlanta's Chipper Jones.
--INF Felipe Lopez raised his hitting streak to six games with three singles. He is 10-for-25 (.400) in that span and is batting .354 since joining the Cardinals in July.
BY THE NUMBERS: 40 -- Number of times the Cardinals scored two or fewer runs in their first 153 games.
QUOTE TO NOTE: "We have to define exactly where the young guys are in their development and what kind of part they'll play next year." -- Pitching coach Dave Duncan, on the offseason meetings to discuss the futures of young relievers Chris Perez, Jason Motte and Kyle McClellan.