And it came with the Baylor rookie's Heisman Trophy-winning college quarterback, Robert Griffin III, playing for the opposition.
Williams caught a touchdown pass for the second straight game, this one on a spectacular throw and catch, on which he combined with quarterback Tony Romo, for the play of the night.
The scoring play went for 15 yards. Romo avoided an outside rush, recovered and lofted a perfect throw into the corner of the end zone that Williams was able to bring down and then keep both feet in bounds.
"Fantastic play," Cowboys coach Jason Garrett said. "It really was."
Williams' season is turning around after some early-season drops and a crucial fumble near the goal line in the Cowboys' 30-21 loss at San Diego two weeks ago.
Since then, Williams scored on an 82-yard touchdown play and had four receptions for 151 yards against Denver last week before his dazzling TD catch on Sunday night, when he finished with two receptions for 27 yards.
"He's got just a lot of will," Cowboys owner Jerry Jones said. "He's a player that it just breaks his heart to mess up, so to speak. He's just continually fighting through that and trying to get better, and you're seeing that right before our eyes."
Williams' rise from a two-star high school recruit to a star at Baylor happened because of the fast-paced practices he went through with Griffin.
That has carried over to the Cowboys, among whom Garrett has praised Williams often for his work ethic and desire to improve.
"He learns from the experience he has, both good and bad, and he really grows," Garrett said. "It's a real tribute to the approach he takes each week."
Williams said he leaned on the work he puts in with Romo during practices to make Sunday night's touchdown catch, an over-the-shoulder grab.
"In practice, it's something that we try to do," Williams said. "Whenever plays break down, you have to find a way to get yourself open."
Williams said he had a brief meetup with Griffin after the game, the first time they've been on opposing teams. His Baylor teammate had an erratic game, completing 19 of 39 passes for 246 yards.
"He just told me he loved me, and I love him back," Williams said. "I told him I'll see him again."