The Cowboys said X-rays were negative and that Williams, expected to be the team's No. 1 receiver after the departure of Terrell Owens, is day to day. The Cowboys have one practice session Monday.
Cowboys owner Jerry Jones said Williams got hurt during the morning practice, and that the concern was that the wrist was still so sore when he returned for the afternoon session. That is when the Cowboys sent Williams for tests.
When Jones cut Owens last spring, the path was cleared for Williams to become quarterback Tony Romo's top target.
"I'm particularly pleased with how focused Roy is, and how conditioned he is," Jones said. "He's having a good camp."
Williams arrived from winless Detroit in mid-October and got a $45 million, five-year contract extension right after Romo sustained a broken pinkie on his throwing hand and missed three games. Williams was then bothered by a foot problem later in the season, plus T.O. was still there.
Williams and Romo started working together several weeks before summer practices, then had OTAs and a mandatory minicamp. And they have been coming together during training camp.
Romo said he wasn't concerned that the injury would stunt their progress.
"Nah, that's part of training camp, little nicks here and there," Romo said. "He's worked his butt off. If anything, it will help him have fresh legs."
Williams caught only 16 passes for 160 yards and no touchdowns in seven games with Romo last season. The lone touchdown pass Williams caught for Dallas was thrown by Brad Johnson during his first two games, when Romo was injured.