"It's not as severe as we first thought," manager Dave Trembley said of Roberts' injury, which suffered in the first inning of Friday's game.
"I'm not able to tell you if it's DL or not. That will be clearer [on Sunday]."
Roberts suffered the injury sliding into the bag on a successful attempt to steal second. The O's leadoff hitter, Roberts walked to open Friday's game, and the impact of the bag hitting his midsection is what is believed to have caused the muscle strain. Roberts said he immediately felt the strain, and after scoring the game's first run, he did not return.
Roberts was starting in his fourth straight game Friday, despite being slowed this spring with a herniated disk in his lower back. Trembley reiterated that Roberts' ab injury is not related to his back, and said that Saturday's report from Bancells was much more optimistic than his original prognosis.
"[Bancells] felt in his first look at Brian [on Friday] that it was going to be a while; today, they aren't so sure if that's accurate or not," Trembley said. "It's certainly somewhat better than first anticipated."
Roberts said he was "definitely really sore" on Friday night, but was encouraged that he woke up on Saturday morning feeling better than expected.
"They want to give it one more day see how it reacts for another night," Roberts said. "I think the second day in will probably give us a better indicator of how long it's going to be."
In Roberts' absence, utility man Julio Lugo filled in on Friday and went 0-for-4. If Roberts is sidelined for an extended amount of time, Lugo and Ty Wigginton will get the bulk of his playing time.
"It's tough not having him in the lineup whether it's one game or five," Trembley said of Roberts.
One of the league's best leadoff hitters, Roberts snapped an 0-for-10 skid with two hits on Thursday night, picking up his first stolen base in the Orioles' 5-4 win against the Rays.
"It's been a rough month and a half so far," Roberts said. "But the great part is we still have 158 games left -- miss a couple now and hopefully I can play the rest of the way healthy."