Scott Rolen had a three-run double and Yadier Molina added a two-run double in the ninth inning off Houston closer Brad Lidge. Rolen and Molina also had RBI singles earlier.
Wells (1-1) allowed one hit and struck out seven in seven innings. He retired the last 16 batters he faced after hitting Chris Burke with a pitch in the second.
Jennings (0-1), who played with Wells at Baylor, gave up five hits, including Pujols' homer, and struck out five in five innings.
Houston fell to 1-5, matching its worst start since 1990.
CINCINNATI - Freddy Sanchez had two hits and an RBI in his first game since coming off the disabled list, and Zach Duke pitched the Pirates over the Reds.
Jason Bay, Jack Wilson and Brad Eldred homered to help the Pirates avoid their first three- game sweep in Cincinnati since September 1998. Wilson hit a two-run shot, while Eldred connected for the first time since 2005 and drove in two runs.
Duke (1-0) pitched six shutout innings before giving up three runs and getting chased in the seventh without getting an out. Salomon Torres pitched a perfect ninth for his fourth save in four tries.
Eric Milton (0-1) fell to 16-24 with the Reds.
WASHINGTON - Livan Hernandez took a no-hitter into the sixth inning against his former team, and the Diamondbacks beat the Nationals to complete a four-game sweep.
Arizona outscored Washington 21-6 in the series, and the Nationals dropped to 1-6, the majors' worst record.
Hernandez (1-0), who threw the first pitch in Nationals history when the Montreal Expos moved to Washington in 2005, didn't allow a hit Sunday until Ryan Zimmerman's ground-rule double with two outs in the sixth.
Jose Valverde pitched the ninth for his third save.
Shawn Hill (0-2) took the loss.
MILWAUKEE - Geoff Jenkins and Gabe Gross hit consecutive homers, and the Brewers got to old nemesis Wade Miller early in a victory over the Cubs.
Miller (0-1) came in with a 6-0 record at Miller Park and an 11-1 mark against Milwaukee.
Chris Capuano (1-0) gave up four runs and four hits in 5 1-3 innings.
SAN DIEGO - Jose Cruz Jr. homered in the eighth inning to tie it and rookie Kevin Kouzmanoff singled with one out in the 10th to snap out of a 2-for-20 slump and lift the Padres over the Rockies.
It was San Diego's second consecutive win against the Rockies, and both came late. On Saturday night, Adrian Gonzalez doubled in Cruz with one out in the ninth for a 3-2 victory.
The Padres had to go extra innings Sunday. Khalil Greene tripled to right-center off LaTroy Hawkins (0-2) with one out in the 10th before Kouzmanoff singled past diving first baseman Todd Helton to bring in the winning run.
Scott Linebrink (1-0) pitched a perfect 10th for the win.
SAN FRANCISCO - Luis Gonzalez hit his first two home runs in Dodger blue and Randy Wolf gave Los Angeles a third straight standout pitching performance to pull off a three-game sweep of the archrival Giants.
Gonzalez connected for a solo shot and three-run homer in his 26th career multihomer game, and Wolf (1-1) outpitched $126 million fellow left-hander Barry Zito (0-2) in the Dodgers' eighth consecutive victory in San Francisco.
MIAMI - The struggling Phillies walked 11 times, but stranded 14 runners and lost to the Marlins.
Touted as title contenders in the NL East, the Phillies are 1-5 for the third time in four seasons and the second year in a row.
Backup catcher Matt Treanor hit an RBI triple, then scored the go-ahead run on a suicide squeeze to help the Marlins overcome an early three-run deficit.
Scott Olsen (2-0) needed 35 pitches to get through a three-run first inning but still earned his second win in two starts. Lee Gardner earned his first career save.
Zack Segovia (0-1) took the loss in his major league debut.