The Pirates announced Monday their plan to add minor league outfielder Andrew Lambo to the active roster Tuesday bringing one of the Pirates' best minor league hitters this season to a team in need of offensive help.

Lambo a left-handed hitter who turned 25 Sunday has a .350 on-base percentage and 31 home runs this season between Class AA Altoona and Class AAA Indianapolis. He hit .297 in his past 10 games.

The Pirates will make corresponding moves to add Lambo to the active and 40-man rosters today. Adding Lambo to the active roster could mean Starling Marte will go on the disabled list because of a left hand injury previously thought not to be serious. The Pirates also could option Alex Presley to Indianapolis.

The Pirates' 40-man roster currently has an open spot so the Pirates don't need to clear one. They also could put pitcher Wandy Rodriguez or catcher Michael McKenry on the 60-day disabled list.

Lambo joined the Pirates from the Los Angeles Dodgers with pitcher James McDonald in exchange for reliever Octavio Dotel at the 2010 trade deadline.

"We acquired Andrew for a reason" general manager Neal Huntington said at the July 31 trade deadline. "It's taken a little bit longer maybe than we'd hoped but he certainly has put up some good numbers this year and is a guy that we do feel with some continued growth some continued adjustments could help us at the major league level at some point this summer."

Lambo's season comes after several up-and-down years in the minors. He hit for average and power in 2007 and 2008 his first two seasons in pro baseball after being drafted in the fourth round of the 2007 draft. Baseball America ranked him as the Dodgers' top prospect after the 2008 season. He plateaued in Class AA in 2009 and 2010.