The San Antonio Spurs received some encouraging news Monday afternoon when an MRI exam came back negative on Tim Duncan's right knee and right ankle, both injured in the first half of Sunday's home victory over Portland.

Duncan has been ruled out of Wednesday's ESPN-televised showdown with San Antonio's longstanding rivals from Dallas, but Spurs' spokesman Tom James said that a firm diagnosis on how long Duncan will be out is at least a day or two away.

The Spurs say they want to see how Duncan responds to treatment before putting an estimate on his return date. But they are treating it as a short-term injury, which naturally comes as a great relief to the defending champs. Things didn't look especially promising when Duncan went down hard after tangling with Portland's James Jones in the second quarter Sunday, with the two-time MVP requiring the help of teammates to leave the floor.

"It's not a big deal at all," Spurs' spokesman Tom James said.