Polamalu, out for the last six games and most of a seventh with a left knee injury, began running in a straight line only Monday. He has yet to begun cutting, turning or twisting, moves needed to play in a game.
Coach Mike Tomlin said Tuesday the five-time Pro Bowl player would be limited if he practices this week. Polamalu said recently he hoped to return for the Dolphins game.
Polamalu also is running in a swimming pool.
"[Monday] was a positive step," coach Mike Tomlin said Tuesday. "The door's not closed on him participating. ... He's just progressing, trying to get him ready, hopefully to play."
The five-time Pro Bowl player will be limited if he practices, Tomlin said. Last week, Polamalu said he probably needed a full week of practice before he could play again.
Several weeks ago, Polamalu pointed to the Miami game for his return. However, he probably must show he can move freely and make sharp cuts on a knee that's mending from a sprained posterior cruciate ligament before he is cleared to play for the first time since Nov. 15.
"Yeah, no question," Tomlin said. "The unanticipated movement that comes with playing football, changing direction, dropping your weight and so forth, will be critical in him getting clearance to play. Absolutely."
Polamalu has played only three full games this season -- all of which the Steelers (8-7) won -- due to two ligament injuries in his left knee. The Steelers must win at Miami (7-8) to retain any chance of making the AFC playoffs.
Wide receiver Hines Ward is expected to play despite having two injured hamstrings. He received treatment on Tuesday, the usual day off for players.
"Hines is miserable, but I'm going to save a seat on the bus for him," Tomlin said. "He's got two hamstrings and a myriad of other issues. It gives him a bad disposition, but he'll show. He's going to leave it out on the field. He's going to give us everything he has."
Backup running back Willie Parker (shoulder) will not practice Wednesday and could miss what might be his final game with Pittsburgh. He is unsigned past this season.