Rasheed Wallace will officially become a Knick on Monday.  Wallace has told the Knicks he has elected to come out of retirement and join their training camp, according to an NBA source.  Read more after the jump.

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The 6-foot-11 Wallace, who worked out with the Knicks over the weekend, retired two years ago after a disappointing season with the Celtics. The Knicks are expected to announce the signing Monday at Media Day. The first practices begin Tuesday.

The tempestuous Wallace, 38, will become the fifth Knick over the age of 35, joining Jason Kidd, Marcus Camby, Kurt Thomas and Pablo Prigioni.

Though contracts haven’t been signed, there are indications Wallace has participated in voluntary workouts in Westchester across the past few days. Pending results of a physical he took Wednesday, Wallace will become Amar’e Stoudemire’s backup at power forward.

Stoudemire has been impressed with Wallace’s lights-out shooting from the 3-point line.

“I don’t know if he signed yet but he has looked good from the time he has been with us,’’ Stoudemire told The Post yesterday during his visit to Rikers Island to speak with adolescent prisoners.

Earlier this week, Tyson Chandler told The Post Wallace looked good in workouts and would be a big help.

Wallace’s agent, Bill Strickland, told The Post yesterday he has not begun contract negotiations with the Knicks and wouldn’t confirm a decision has been made. Not much negotiation needs to be done, as Wallace would stand to make the veteran’s minimum of $1.7 million.

Strickland would only say if Wallace comes out of retirement, it would only be with the Knicks because of his relationship with coach Mike Woodson, the Pistons assistant under Larry Brown when Detroit won the 2004 title.

The Knicks look at the move as no-risk, high-reward. If it doesn’t pan out and even if Wallace decides to retire again, the team still has Thomas as a backup power forward. Wallace is a stout help defender and rebounder.

Woodson pushed for the move, which could also signal the Knicks being concerned about the durability of Stoudemire, who has broken down in both of his playoff appearances with the Knicks because of a chronic back issue.

There’s a notion Wallace retired after the 2009-10 season because he no longer had the dedication to get in NBA shape and finished the Celtics year in poor condition. However, his mother — now in good health — was ill at the time of Wallace’s retirement, and that could have been a factor in his decision.

NY Post