Fontenot also swings a left-handed bat, something the Phillies have plenty of after acquiring outfielder Nate Schierholtz and calling up outfielder Domonic Brown from Triple-A Lehigh Valley on Tuesday.
Martinez, a switch-hitter who was a mainstay on the 2011 roster, played 16 games for Philadelphia in June, starting 13 times at second base. He was 6-for-45 with a home run and four RBIs. Manager Charlie Manuel said Martinez could act as a defensive replacement at third base late in games or spell Chase Utley or Jimmy Rollins if either need a day off.
Fontenot hit .289 with a home run and five RBIs in 47 games, but was just 1-for-15 against left-handed pitchers.
"He swung the bat good off the bench as far as from the left side," Manuel said. But right now we're loaded with left-handed hitters."
Jake Kaplan is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.