Facing his former team could provide extra motivation to finally take the field.
The Seahawks are hoping to have Harvin available for the first time when they go for a sixth consecutive win Sunday against the visiting Minnesota Vikings.
Seattle (9-1) has established itself as one of the NFL's most complete teams, ranking third in total defense with 289.0 yards allowed per game and scoring 26.5 per contest to rank sixth.
The Seahawks climbed 2 1/2 games ahead of second-place San Francisco in the West with last Sunday's 33-10 rout at Atlanta. Russell Wilson completed 19 of 26 passes for 287 yards and two touchdowns while Marshawn Lynch ran for a season-high 145 yards and a score.
The Seahawks haven't won six straight in a season since a franchise-record 11-game winning streak in 2005. They are 12-0 at home since the start of last year.
"We've got more games we have to win and we have a lot of work to finish it out," coach Pete Carroll said. "We have a chance to do something special in this division, we need to take advantage of every opportunity and win every game going down the stretch."
Seattle has to be feeling good about its chances of doing just that with Harvin at its disposal. The former Pro Bowl wideout, who was acquired from Minnesota in March in exchange for a package of draft picks, had been on the physically unable to perform list since the start of training camp with a serious hip injury but was added to the 53-man roster Monday.
Harvin had 62 receptions for 677 yards and five total TDs - including a 105-yard kick return - last season before missing the Vikings' final seven games with an ankle injury.
"He just has to practice every day and show that what he's done in the rehab has paid off and that he can sustain through each day," Carroll said. "It's really the next day that we always look at. ... We'll just see how it goes. To us it's not a pressure decision."
The Seahawks, who head into their bye following Sunday's game, also have decisions to make on offensive linemen Max Unger (concussion), Russell Okung (toe) and Breno Giacomini (knee) and defensive end Red Bryant (concussion).
"It's two weeks that we could buy. We have that in mind," Carroll said. "We're going to take the information and evaluate each guy and figure out what it means, knowing that we're OK. We're OK where we are, so we're not pressed into making a decision hastily."
While the Vikings (2-7) snapped a four-game losing streak with last Thursday's 34-27 win over Washington, that result may have come at a cost. Christian Ponder was 17 of 21 for 174 yards and two scores before dislocating his non-throwing shoulder trying to dive for a touchdown, leaving his status unclear.
"When they see that tape and see that he extended his body the way he did, it's going to increase their appreciation for who he is as a person and what he means to our team as a quarterback," coach Leslie Frazier said.
Whoever lines up under center faces a tough challenge against a Seahawks defense giving up just 178.0 passing yards per game, the league's second-best mark. Although Seattle is all but certain to be without star cornerback Brandon Browner due to a groin injury, Carroll doesn't expect his team to miss a beat.
"We're in good shape at the position," Carroll said. "If we're going to miss Brandon, it's going to be significant because he's a terrific player for us, but we do have really capable guys to step in."
Ponder went 11 for 22 for 63 yards and was picked off by Browner in a 30-20 loss at Seattle last November. Adrian Peterson, though, ran for 182 yards and two touchdowns on 17 carries.
Peterson, who also scored twice against the Redskins, leads the NFL with nine rushing TDs. His 87.3 rushing yards per game rank third in the league.
Vikings wideout Jerome Simpson is likely to play despite his arrest on suspicion of drunken driving last weekend. Simpson has compiled a team-leading 491 receiving yards.
Former Seahawks tight end John Carlson, who had seven catches for 98 yards and a touchdown versus Washington, faces his former team for the first time.