Nowitzki, averaging 26.9 points and 10.1 rebounds, missed his second straight game because of a bruised left knee.
Dallas starters Michael Finley (bruised calf) and Erick Dampier (stress fracture, foot) also were out along with sixth-man Jerry Stackhouse (groin injury). The Mavericks had only nine players in uniform.
“We had to have it tonight,” said Mavs guard Jason Terry, who scored 23 points. “Everybody stepped up and made plays. Our big guys were out so we needed it from everyone. Marquis and Josh really played well in the fourth.”
Van Horn went 8-for-13 from the floor in his second start for Dallas since being acquired in a trade with the Milwaukee Bucks on Feb. 24. He had 15 points at the half.
“This was the best I’ve felt since I’ve been here,” said Van Horn, who shot 37 percent from the field in his first five games for Dallas. “I was more active on both ends. But I had to because when you’re missing All-Stars, somebody has to step up.”
The Mavericks began the fourth quarter with an 11-5 spurt, capped by Daniels’ 15-footer with 7:35 left that gave Dallas a 95-81 advantage.
Toronto got as close as 103-99 on Milt Palacio’s basket with 1:35 to go.
But Daniels hit a 15-footer with 1:09 left and had a steal on Toronto’s next possession to close out the Raptors.
Coach Don Nelson called plays down the stretch to get shots for Daniels.
“I think (Nelson) is really trying to build my confidence because I haven’t been playing that well,” Daniels said. “But I got a lot of opportunities tonight and everything just clicked.”
In the second half, Nelson made extensive use of a small lineup that included the 6-foot-9 Henderson at center.
Morris Peterson scored 23 points, and Palacio had a season-high 19 for Raptors, who had won four of their previous six.
Dallas native Chris Bosh had only 13 points for the Raptors after scoring 33 in Sunday’s victory at New Orleans.
“They did a good job of doubling and getting the ball out of my hands,” Bosh said. “I struggled all night. But I’ve got to give them credit. They’re quick and they made shots. That’s always tough to beat.”
The Mavericks ended the third quarter with an 11-4 run to take an 84-76 edge into the final quarter. Dallas was in front by as many as 15 in the second quarter and held a 57-53 halftime lead.
Toronto coach Sam Mitchell said the difference in the game was the quickness and speed of Dallas’ young players.
“We’ve got to give them credit,” Mitchell said. “They were short-handed but we had no answer for their athleticism. They had 54 points in the paint, but all of those points were putbacks and layups.”
Peterson left the game briefly in the second half because of a cut on his head that required stitches to close. … Referee Jimmy Clark needed medical attention in the second quarter after colliding with Toronto’s Rafer Alston. Clark was sprinting upcourt to get into position on a fast break when he ran into Alston, bumping his head on Alston’s elbow. Clark was down for several minutes before going to the locker room for treatment while the game went on with two referees. Clark was back on the court about 4 minutes later. Alston was uninjured. … Nowitzki and Finley are expected to return Thursday night for a home game against the Los Angeles Lakers. Stackhouse is expected to be placed on the injured list.