This is good news for the Ravens (10-7), who have a short week to prepare for Saturday's postseason game against the Indianapolis Colts (14-2).
Heap suffered a stinger in the fourth quarter of Sunday's 33-14 victory over the New England Patriots. The source described Heap's back Monday as "pretty sore." The two-time Pro Bowler is scheduled for further testing this week, and his playing status likely won't be finalized until closer to game time.
During his Monday press conference, Ravens coach John Harbaugh was optimistic about Heap's chances of returning.
"He's got some lower-back-type spasms," Harbaugh said. "That stuff can be tough, but usually you can work through that pretty well. So he should be fine."
During the regular season, Heap recorded 53 receptions for 593 yards and six touchdowns for the Ravens. He was the team's third-leading receiver.
James Walker covers the AFC North for ESPN.com.