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LOS ANGELES (Reuters) - Blake DeWitt hit his first home run of the season and recorded a career-high five RBIs to lead a slug-fest for the Los Angeles Dodgers in their 12-4 rout of the St Louis Cardinals on Monday.

The diminutive second baseman began with an RBI single in the fourth inning, where the Dodgers scored four times, before he smacked a line drive over the right-field fence in the fifth as the home team added four more runs.

"It felt good to get the monkey off my back," DeWitt told reporters of his first homer. "Up and down the lineup we strung together good at-bats and made their pitchers work. It was a good night."

The big margin was a rare blowout for Los Angeles (34-24), who had triumphed by just one run in each of its last seven victories.

"That's what happens during the season... sometimes you catch a game where things go right for you," Dodgers manager Joe Torre said. "We had a couple key innings. The back-to-back four-run innings were big for us."

Los Angeles rookie pitcher Carlos Monasterios improved to 3-0 after tossing six innings and allowing three runs.

Ryan Ludwick hit two solo home runs for the Cardinals (33-25), who gave Blake Hawksworth his first career Major League start, though he allowed six runs over four innings and was replaced.

St Louis trailed just 2-1 before the Dodgers began the onslaught in the fourth, stringing together consecutive hits to move runners along.

Reliever P.J. Walters came on in the fifth for the Cardinals and allowed the last six runs.

Los Angeles finished the game with 14 hits and won for the seventh time in nine contests.

(Reporting by Jahmal Corner in Los Angeles; Editing by John O'Brien)