The acquisition gives the Cowboys a proven receiver opposite Terrell Owens. The winless Lions traded their unhappy 2004 first-round pick for first-, third- and sixth-round draft picks in 2009. The Lions also gave the Cowboys a seventh-rounder.

Cowboys owner Jerry Jones said he struck the deal two minutes before the deadline.

"I'm more happy to be a Dallas Cowboy then when I got my first bike," said Williams, an Odessa native who played at the University of Texas.

Williams' best season was 2006, when he went to the Pro Bowl after making 82 catches for 1,310 yards and seven touchdowns. He has 17 receptions for 232 yards and one touchdown in 2008.

After announcing the deal, the Cowboys said they had given Williams a five-year extension on a contract that was set to expire after this season.

The news came hours after the Cowboys learned Adam Jones had been suspended by NFL commissioner Roger Goodell for at least four games and two days after quarterback Tony Romo suffered a hand injury that could sideline him for a month.

Williams said the first phone call he received after the trade was from Cowboys receiver Terrell Owens, and owner Jones said Owens was "elated and beside himself."

"We got two guys out there that can really run, they're big, but as you know, both of them can really make spectacular catches," Jerry Jones said.

Williams is expected to begin practicing with the Cowboys on Wednesday, and play on Sunday at St. Louis.