The short-handed Kings looked formidable against the Mavericks.
Earlier in the day, the Kings completed a seven-player deal with Toronto that brought them Gay, Aaron Gray and Quincy Acy. Greivis Vasquez, Patrick Patterson, John Salmons and Chuck Hayes went to the Raptors.
"I guess I came on a good day because the team was playing great," said Gay, a veteran forward who is expected to make his Kings debut Wednesday at home against Utah. "Obviously DeMarcus and Derrick played well. So this is a good start and I can't wait to get out there with the guys."
A proven scorer, Gay will no doubt add more punch to a Kings lineup that has been unproductive at times this season. He was Toronto's second-leading scorer and has averaged 18 points and 5.9 rebounds in his eight-year career.
On this night, the Kings showed plenty of offense without Gay. Sacramento shot 47 percent, had 23 assists, and outscored the sluggish Mavericks 24-3 on fast-break points. Using just 10 players, the Kings led by 19 points after three quarters and by as many as 24 in the fourth in winning their second straight.
"We didn't care if we had 10 or 15 players, we had enough talent to win this game," Kings coach Michael Malone said. "... Our next challenge is to figure out the new guys and how they're going to play and at what position."
Malone knows one thing -- Isaiah Thomas will be his starting point guard.
Thomas had 24 points and a career-high 12 assists, and Jason Thompson added 10 points and seven rebounds for the Kings. Sacramento has played 13 of its 19 games at home this season, going 4-9.
With Vasquez, the starting point guard gone, Thomas made his first start of the season. The team's second leading scorer and one of the NBA's most productive reserves, he got off to a great start, getting 10 points and three assists in the first quarter when Sacramento established an 11-point lead.
"That little Isaiah and DeMarcus Cousins are a handful," Dallas forward Shawn Marion said. "That's a heck of a duo right there."
Production from Cousins and Thomas, Sacramento's leading scorers this season, was predictable. What was unexpected were the contributions by Williams, who had struggled a bit since arriving in a trade with Minnesota on Nov. 26.
Williams hit 12 of 16 shots and connected on three 3-pointers, one more than he had made entering the game. He also added five rebounds and a career-high five steals.
"I finally hit a 3-point shot," said Williams, who was 0 for 5 with the Kings and 2 of 25 overall entering the game. "It's good to make that first shot, and it's good when the first couple go in."
Monta Ellis had 21 points for the Mavericks, who had won three straight, including the last two on the road. The loss also snapped a five-game win streak against the Kings. Dallas had won 15 of the previous 16 meetings and was 23-3 against the Kings dating to April 4, 2006.
Dirk Nowitzki had 18 points, Jose Calderon scored 11 and Shane Larkin had 10 for Dallas. Coming off an impressive win Saturday at Portland, the Mavericks shot 40 percent and were 5 of 27 on 3-pointers.
"I don't think we took them lightly, I think they just outplayed us," Dallas coach Rick Carlisle said. "It was one of those nights where they made a lot more plays than we did."
Sacramento continued to play well offensively in the third quarter, outscoring the Mavericks 35-26 to take a 92-73 lead. Williams made a pair of 3s, had two impressive dunks, and scored 13 points. Both Thomas and Cousins had 11 points.
The Kings squandered a 16-point lead in the second quarter, but scored 13 unanswered points in taking a 57-47 lead into the intermission. Ellis scored 13 points for Dallas.
Sacramento outrebounded the Mavericks 29-14 in the first half and 51-39 overall. ... Dallas concludes a four-game road trip Wednesday at Golden State. ... Center DeJuan Blair started his fourth straight game, but was relatively ineffective with four points and four fouls in 14 minutes. ... Rookie guard Ray McCallum made a jumper with just under a minute to play for his first NBA points. He had played only one minute previously. ... Cousins had nine of Sacramento's 21 turnovers.