Beltre was not in the original lineup Thursday night against Cleveland, a day after injuring his left shoulder.
The All-Star third baseman talked to Washington and was later listed as the designated hitter.
"He strong-armed me," Washington joked.
Rangers center fielder Josh Hamilton was out of the lineup. The 2010 AL MVP left Wednesday night in the eighth inning and received an injection for his sore left knee.
Washington doesn't consider Hamilton's injury serious and he is expected to play Friday night against Seattle. Leonys Martin will start in place of Hamilton, who came in leading the majors with 41 home runs and 121 RBI.
Beltre, who has hit 13 home runs in his last 20 games, hurt his shoulder diving for a ground ball at third base and left in the fifth inning. An MRI on Wednesday night revealed slight inflammation.
"They assumed I wasn't going to feel good based on what they saw last night," Beltre said. "But today is a different day."
Texas catcher Mike Napoli worked out with the Rangers after catching nine innings in a rehab assignment for Double-A Frisco on Wednesday night.
Napoli, who has been on the disabled list since Aug. 11 with a left quadriceps strain, will be the designated hitter for Frisco on Friday and could be activated Saturday.
"My timing is almost there," Napoli said. "I felt good behind the plate."
In other injury news, Texas infielder Mike Olt is expected to miss 10-to-14 days because of plantar fasciitis on his right foot. The rookie had an MRI and visited a foot specialist Thursday.
Olt replaced Beltre on Wednesday, but left after beating out an infield single in the seventh inning.
Rangers reliever Robbie Ross will throw in the bullpen on Friday. The left-hander has been on the disabled list since Aug. 30 with a strained left forearm.