PITTSBURGH (AP) -- The Red Sox are hoping this latest trade for Pittsburgh's leading power hitter turns out as well as last season's.

The Red Sox acquired slumping first baseman Adam LaRoche on Wednesday for two midlevel prospects, less than a year after they picked up All-Star outfielder Jason Bay from the Pirates.

"I'm grateful for the opportunity that a team like that wants me," said LaRoche, who is hitting .109 since July 4.

Later in the day, Boston traded SS Julio Lugo to St. Louis for OF/1B Chris Duncan and a player to be named later, SI.com has confirmed. (The Cardinals also received cash considerations in the deal.) Lugo, in the third year of a four-year, $36 million deal, had fallen out of favor in Boston. The Red Sox designated him for assignment last week. Duncan, hitting .227 with five homers and 32 RBIs, had been optioned to Triple-A Memphis by the Cardinals before the deal was made.

The Pirates, who have traded five starting position players since last July, will receive Double-A shortstop Argenis Diaz and Class-A right-hander Hunter Strickland, an 18th-round draft pick two years ago.

The deal possibly clears the way for Pittsburgh to deal shortstop Jack Wilson before the July 31 deadline for trading without waivers, and, maybe, NL All-Star second baseman Freddy Sanchez.

The Red Sox lost their fourth consecutive game Tuesday night to fall out of first place in the AL East, a game behind the New York Yankees. Boston was pursuing Toronto starter Roy Halladay, but a bat turned into the bigger priority for a team that is hitting .236 since June 17 and has scored 12 runs in five games since the All-Star break.

"We've been in the market for a player who can do some damage against right-handed pitching and help our depth at the corner infield," Red Sox GM Theo Epstein said in a conference call. "This was a chance to get at a very reasonable acquisition cost a player that ... leaves us in condition to look for more impact before the trading deadline."

The trade was first reported by the Pittsburgh Post-Gazette on its Web site.

LaRoche, eligible for free agency after this season, is hitting .247 with 12 homers, 40 RBIs and 81 strikeouts in 87 games. He is 5 for 46 the last 21/2 weeks -- 0 for 22 at one point -- with one RBI and 16 strikeouts.

"Not real good, not real good," LaRoche said of his time in Pittsburgh. "Looking back, I'm a little disappointed because I know what I'm capable of doing and what I should be doing, but I wasn't able to put it together over a six-month season. I was too streaky."

LaRoche may take some at-bats away from utility backup Mark Kotsay while giving third baseman Mike Lowell more time to rest his ailing hip.

The Pirates will recall Steve Pearce from Triple-A Indianapolis and plan to play him regularly at first starting Thursday at Arizona. He was 1 for 12 during a brief callup earlier this season.

The 29-year-old LaRoche was expected to supply a much-needed left-handed power bat when the Pirates dealt left-handed reliever Mike Gonzalez to Atlanta for him in January 2007, but he hasn't hit better than .272 in two-plus seasons and got off to poor starts in 2007 and 2008.

LaRoche hit 32 homers for Atlanta in 2006, but his best season with Pittsburgh was 25 homers and 85 RBIs a year ago. He signed a $7.05 million contract this season to avoid arbitration, and the Red Sox will pick up all of estimated $3 million still owed him.

"Why it didn't work here? At times, he was very good and at times it was a struggle," Pirates GM Neal Huntington said. "He didn't show a lot of energy, didn't show a lot of passion and fire, but this was a guy who cared a lot and did a lot of good things for us in the clubhouse."

The Red Sox hope they're adding a bat who can complement Bay, who went into Wednesday's games with 72 RBIs, third most in the AL. The Pirates, by contrast, have gotten little out of the July 31, 2008, deal that was highlighted by Manny Ramirez going from Boston to the Dodgers; one of their pickups, younger brother Andy LaRoche, has four homers and 36 RBIs as their third baseman.

Diaz, a 22-year-old known for his outstanding defense, is hitting .253 with no homers and 24 RBIs in 76 games during his sixth pro season, at Portland. He will move up to Indianapolis, where he becomes Wilson's heir apparent.

Strickland, 20, is 5-4 with a 3.35 ERA in 18 games, including 12 starts, at Greenville of the South Atlantic League. He will shift to West Virginia of the same league.

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