The wide receiver, who wants a long-term contract and hasn't signed his tender offer from the Steelers, is expected to report to the team before the regular season begins, people who have spoken to him told ESPN NFL Insider Adam Schefter on Tuesday.
The Steelers refuse to negotiate with Wallace on a new deal until he shows up and signs his one-year, $2.7 million tender.
Wallace, a starter in the Pro Bowl last season, did not take part in any of the Steelers' offseason workouts or minicamp.
Quarterback Ben Roethlisberger told 93.7 The Fan in Pittsburgh last week that the holdout wide receiver is staying in shape.
"I gave him a call to wish him happy birthday and see how he was doing," Roethlisberger said. "And Mike's training hard. He's training with his helmet on just like he'd be here. So he's doing a lot of things. And I have confidence he'll be here and ready to go for the season."
While talks with Wallace have stalled, the Steelers signed fellow Pro Bowl receiver Antonio Brown to a five-year, $42.5 million extension last month.
In the first three years of his career, Wallace has 171 receptions for 3,206 yards with an average of 18.7 yards per catch. He has 24 touchdowns.
Last season, Wallace's 1,193 receiving yards ranked 11th in the NFL. And his 21.0 yards-per-catch average in 2010 was tops among players with at least 50 receptions. Wallace was having one of the best statistical seasons in the NFL last season with 43 catches for 800 yards and five touchdowns through October.
But he struggled late in the season. In fact, Wallace did not have a 100-yard game after Oct. 23 and did not have a touchdown in seven of his final eight games, including a three-catch, 26-yard performance in a 29-23 overtime playoff loss to Denver.
Information from ESPN NFL Insider Adam Schefter, ESPN.com AFC North blogger Jamison Hensley and The Associated Press was used in this report.