Smoak, who was hitting .326 (15-for-46) with two homers and 15 RBIs in Oklahoma City, will make his major league debut against the Detroit Tigers on Friday night.
"Justin has been having really quality at-bats at Triple-A and we just felt we could use more production out of that spot in the lineup," Rangers general manager Jon Daniels said Thursday. "We want to see if he can continue to have those high quality at-bats in the big leagues."
Davis, meanwhile, was batting .188 with no homers. He has one RBI all season and it's the only RBI for the club at first base. That's last in the American League.
"Chris is working hard," Daniels said. "He's putting the time and the work in. It's early in the season but I think if this had been Chris' first exposure to the big leagues, we would have been inclined to wait. But we've got a quality option performing at Triple-A. We felt like offensively we're not clicking yet as a club and this was an opportunity to help in that regard."
Smoak, 23, was the club's first-round pick (11th overall) in the 2008 draft. To make room on the 40-man roster, the Rangers recalled right-handed pitcher Omar Poveda and placed him on the 60-day disabled list.
The switch-hitting Smoak seemed to jump-start his play with a solid showing for Team USA in September last year. He hit .291 with nine homers, 22 RBIs and 16 runs scored, and was voted the tournament MVP as the U.S. won a gold medal. Smoak played for three seasons at the University of South Carolina before he was drafted by Texas.
"We're not looking at Justin Smoak to ride in on a white horse and save the day," Daniels said. "We just want him to play good defense and get us four-five quality at-bats a night. The rest will take care of itself. There are other spots in the offense that are off to slow starts. But this is a position where we have some depth in the system and a guy we feel that can help us right now."