Manager Joe Maddon was more tentative in assessing Upton's strained left quadriceps, saying he would have to be "really convinced" that his leg was fine before sending him to the plate.
Upon meeting with the media on Monday night, the Rays skipper had yet to speak with Upton about the injury and confer with head athletic trainer Ron Porterfield on his most recent progress.
Upton suffered the injury running down David Ortiz's double in the first inning at Fenway Park on Sept. 8. Since then, the 24-year-old has been making slow but steady progress in his quest to return. Upton ran on a treadmill on Sunday, and he tested his legs further on Monday by running on the artificial turf at Tropicana Field and taking swings in the batting cage.
While Upton has stressed not rushing his return, he was hopeful that he would be able to swing the bat on Monday and be inserted back into the lineup for Tuesday's game.
Prior to the injury, Upton was hitting .274 with eight home runs and 64 RBIs, despite dealing with a torn labrum in his left shoulder that has limited his power.
In his absence, Maddon has predominantly used the speedy Fernando Perez, granting the outfielder his first start at Tropicana Field on Monday. Perez made three starts in center field during the Rays' recently wrapped nine-game road trip, and he has appeared in every game since he was called up from Triple-A Durham on Aug. 31.
While Maddon was unsure whether Upton would be available on Monday night, he was definitive in his assessment of closer Troy Percival.
"He's feeling a little bit better," Maddon said. "And he will be available [Monday night]."
Percival has not taken the mound since loading the bases in the 14th inning on Wednesday, exiting with back tightness after being unable to record an out. The veteran hurler has been taking muscle relaxers to help combat the problem, and Maddon was encouraged by his talk with Percival on Monday afternoon.
The Rays are 34-1 when Percival enters the game in save situations.
Brittany Ghiroli is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.