" As Jason Terry said on the road trip through the frozen North, the Mavericks wish somebody would run over that black cat that keeps following them.

They could use some good news from the injury front. But the way their luck's running, they aren't counting on it.

The evaluation of Caron Butler's right knee began Monday, but the Mavericks were not releasing details of his injury and information about the starting small forward's prospects for returning this season may come today.

The team is braced for bad news but hoping that Butler's season isn't over.

The best glimmer of hope is that after missing four games with a sprained right knee that has bothered the back of the joint rather than the front, Dirk Nowitzki is closer to returning. He said over the weekend trip that he hoped to be back in action this week. Whether it's tonight against the Portland Trail Blazers to start a three-game homestand or sometime later in the week, it should be soon.

That will make everybody's life a little less stressful, even with Butler lost for an indefinite period.

The Mavericks hope that Nowitzki returns tonight, but he may need more time. Nowitzki has been limited to mostly flexibility, cardio and muscle-strengthening work for the last week.

In the games Nowitzki has missed, the Mavericks are 1-3 and have realized how tough it can be to score without the double-teams Nowitzki draws to open space on the floor for teammates.

"Everybody's going to have a tougher time getting great shots without Dirk out there," coach Rick Carlisle said. "That's just going to be a fact of life. Right now, we just have to execute a little better."

In particular, Jason Terry has had difficulty finding good shots. He and Nowitzki work a two-man game often, particularly at crunch time, and it's hard to make that action work when one component is missing.

"The last couple of games have been difficult," said Tyson Chandler. "Guys have been playing different roles. Some guys have been playing more minutes and at different positions. That's tough to adjust to right away. And it's especially tough when it comes to communicating on defense. If you can't communicate, then you're trying to do it on the fly."

Chandler said that the loss of Butler – and his teammates seem to think this is not a short-term injury – is something that's going to be very challenging to overcome. "