SAN DIEGO -- "Middle/middle" is not a good place to be if you are a starting pitcher.

Which is exactly where San Diego Padres left-hander Travis Wood was locating some of his more important pitches Tuesday night.

"If it wasn't for me, we would have pulled this out tonight," Wood said after he gave up seven runs in two-plus innings as the St. Louis Cardinals posted an 8-4 victory over the Padres at Petco Park.

First baseman Jose Martinez drove in three runs with a pair of home runs, and center fielder Harrison Bader added a three-run homer as the Cardinals scored a second straight win in the first two contests of a four-game series.

Martinez gave the Cardinals a quick two-run lead with his 12th homer in the first off Wood. He added a solo homer in the seventh off Padres left-handed reliever Buddy Baumann.

"I think it's the confidence, man," Martinez said of his two homers against lefties. "I'm just trying to do the best I can. Even when I wasn't playing much earlier in the year, I was getting mentally ready. It has started to pay off in the last month."

"He just had a great day," Cardinals manager Mike Matheny said of Martinez, who also had a double and a walk and scored three runs. "He has come up with big at-bats in big situations. He has had some great at-bats."

Bader, who was promoted from Triple-A Memphis as a September call-up, put the Cardinals ahead to stay with a three-run homer in the second off Wood (2-2). The first two home runs came with two outs.

"I'm just more relaxed," Bader said. "It's just a feeling that you belong. I think some young players struggle with that aspect, but you're here for a reason."

Meanwhile, Cardinals starter Michael Wacha (11-7) held the Padres scoreless over his final 4 2/3 innings. In all, he allowed four runs (three earned) on seven hits and three walks with six strikeouts in six innings.

"He regained his composure," Matheny said. "He is growing as a pitcher on how he is using his stuff."

The Cardinals built a 7-4 lead against Wood in a wild first three innings.

"Too many middle/middle mistakes," Padres manager Andy Green said of Wood. "He just wasn't locating."

Wood said, "I felt good. I left the ball up and made some mistakes, and they didn't miss my mistakes."

St. Louis got on the board first when Martinez hit an opposite-field, two-run homer in the first. Bader opened the game with a single, but Wood retired the next two Cardinals before Martinez hit a high, 386-foot drive.

The Padres tied the score in the bottom of the first. Jose Pirela drew a two-out walk, moved to second on a single by Yangervis Solarte and scored on a single by Wil Myers. Solarte then scored on a wide throw to third by center fielder Bader when no Cardinal was covering home.

St. Louis upped the lead to 5-2 in the top of the second on Bader's homer, a 378-foot rocket to left. Stephen Piscotty drew a walk to open the inning and moved to third on Alex Mejia's one-out single. However, Piscotty was out at the plate when Wacha bunted directly to first baseman Myers. Bader followed with his blast.

Wood temporarily helped his cause in the second with a two-run homer off the face of the second balcony of the Western Metal Supply building in left. The homer was Wood's second in as many starts.

The Cardinals drove Wood from the mound in the third. Paul DeJong opened the inning with a single, moved to third on Martinez's double and scored on Yadier Molina's grounder to short. On the play, Martinez reached third on a throwing error by Solarte, and he scored on Piscotty's single.

Wood gave up seven runs (six earned) on seven hits and a walk with a strikeout in two-plus innings.

NOTES: Cardinals INF Matt Carpenter, who left the Monday game with a sore right shoulder, had a MRI exam Tuesday. The results showed no serious injury, although Carpenter could have an injection and miss several games. ... The Cardinals promoted 2B Breyvic Valera from Triple-A Memphis, where he hit .314. ... OF Dexter Fowler's hip improved to the point where he could have played Tuesday, but the Cardinals elected to hold him back one more game. ... The Padres are inserting RHP Jordan Lyles into what will become a six-man rotation. In his first start for the Padres in the second game of a Saturday doubleheader against the Dodgers, Lyles allowed two runs on six hits and four walks with three strikeouts in 4 1/3 innings. ... There were four runners thrown out on the bases Tuesday night, three by the Padres, who also committed two throwing errors.