Perez is on the disabled list with a fracture in the tip of his right thumb. He has been able to throw during his time off and is eligible to come off the disabled list Monday. He threw a bullpen session Friday with the idea of being ready to start that day against the Red Sox.
"I'm good. ... I'm ready to pitch," Perez said.
Manager Jeff Banister wants to make sure Perez can field his position. He has extra padding in his glove to protect the thumb, and that will help him be ready for Monday.
"That would be the target date," Banister said.
Darvish, who started Wednesday in Cleveland, would normally pitch Monday on four days' rest. But going with Perez would give Darvish an extra day at a time when he has been dealing with tightness in his right triceps.
It would also give Andrew Cashner an extra day. He had some soreness in his right forearm Friday after getting hit by a broken bat in Thursday's outing against the Indians.
"We want to give him every opportunity to get the soreness out and be able to compete," Banister said.
That would set the Rangers up for Darvish and Cashner to pitch in the final two games of the series against the Red Sox. The Rangers are off on Thursday, then close out the first half with three games against the Twins. Cole Hamels would pitch the first game, followed by either Perez or Tyson Ross on Friday.
The plan then would be for Darvish to pitch on Sunday in the final game before the All-Star break. Darvish could also be selected to the All-Star Game, and it would be his decision on whether he can pitch. Darvish would have to commit to being able to throw 20 pitches in the All-Star Game or he would be replaced on the roster.
Barnette rejoined the Rangers after throwing two scoreless innings for Triple-A Round Rock on Thursday. He also had a scoreless inning on Tuesday and threw a total of 40 pitches over a three-day period. The Rangers likely will give him a couple days off before activating him.
Barnette has been on the disabled list since June 15 due to a sprained right ring finger, but the time off was also used to work on and slow down his delivery. That seemed to be a significant issue for the reliever, who had a 7.23 ERA in 23 games.
"I feel good. It was a successful trip," Barnette said. "Everything was working well, and the finger was not an issue."