Caron Butler, one of the Dallas Mavericks' six unrestricted free agents, has been rehabbing from his knee injury in Chicago, and there's mutual interest between the Bulls and the two-time All-Star:

As the NBA free-agency period begins the test-the-waters mode, Butler's interest in the Bulls is legitimate, according to league sources. One source close to Butler said that Butler said early Thursday morning, "I hope I don't have to leave."

Interest in Butler is widespread. The Spurs, Heat,Clippers and Bulls are among the teams that expressed serious interest in him on Wednesday, the first day teams could contact agents.

Chicago, an elite team whose lack of perimeter offense next to Derrick Rose was exposed in a 4-1 loss to the Miami Heat in the Eastern Conference Finals, seems like a good fit for Butler. 

In 29 games with the Mavericks before tearing his knee in January, Butler averaged 15.0 points and 4.1 rebounds, while playing solid perimeter defense and shooting a career-high 43.1% from the three-point line.

He's rumored to want the full mid-level exception, which would be a significant problem for Dallas, as they are already struggling to re-sign Tyson Chandler without jeopardizing their 2012 cap space. 

The Mavericks were able to survive Butler's injury last year by increasing Shawn Marion and DeShawn Stevenson's playing time, and they acquired Rudy Fernandez in a draft-day trade from Portland in an effort to cover their bases on the perimeter.