Beckett threw on flat ground before Saturday's game against the Twins, and played long toss out to about 120 feet, looking unrestricted as he did so.
"Great," Valentine said. "He really felt good today and we're going to try to insert him on Wednesday."
By pitching Beckett Wednesday, Valentine could get lefty Felix Doubront, and conceivably the other pitchers in the rotation, an extra day of rest.
Wednesday was Doubront's original day to pitch. Doubront has thrown 118 1/3 innings this season, meaning he will easily pass his professional career high of 129 1/3 for Class A affiliates Lancaster and Greenville in 2008.
In 21 starts, Doubront is 10-5 with a 4.56 ERA. He couldn't hold a 5-1 lead on Friday night, a game the Red Sox lost in 10 innings.
"Felix Doubront is a first-year starter in the American League, in the American League East, in Boston, Massachusetts," Valentine said. "We want to look at a perfect, finished product in a guy who's doing an outstanding job. I'm not looking at perfection. I've seen a great deal of excellence. I love the excellence that I've seen, and I think we can build on that."