Harrison twisted his ankle early in Wednesday night's game, and was only a long shot to be available off the bench Thursday. He had started in place of Neil Walker, who is on the 15-day disabled list recovering from an appendectomy.
Other than having to do it in an ankle brace, Harrison appeared to be walking around the clubhouse comfortably. He deferred questions about his condition to manager Clint Hurdle.
"He's gone through different tests and drills," Hurdle said, "and the best thing to come out of that is, we don't feel he's a DL candidate. We think he's improved. He could possibly be used off the bench tonight."
Martinez signed a Minor League contract with Pittsburgh in December after refusing a Minor League assignment by the Phillies, for whom he had appeared in 29 games last season, and 162 from 2011-13.
A versatile defensive and offensive player, the 31-year-old Martinez is a pepper pot 5-foot-9 switch-hitter able to play anywhere in the outfield and the infield, with the exception of first base.
He was batting just .229 in 61 games with the Indians, but he had hit .382 in 18 Grapefruit League games this spring.
Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. Teddy Cahill is a reporter for MLB.com. Follow him on Twitter at @tedcahill. This story was not subject to the approval of Major League Baseball or its clubs.