Gay had 15 points for the Kings, who acquired him in a seven-player deal on Dec. 9. The game marked Gay's first trip back since he was shipped with Aaron Gray and Quincy Acy to Sacramento for Greivis Vasquez, Patrick Patterson, John Salmons and Chuck Hayes.
"We have to treat them like an enemy rather than a friend because we all have friends on that team," Patterson said. "Going into this game, we have to treat it like they're the enemy, as if they're a villain and we're a superhero pretty much.
"We can't be friendly with them."
Patterson and DeMar DeRozan each scored 15 points, while Jonas Valanciunas added 14 points and Amir Johnson had nine rebounds to go with nine points for the Raptors, who've won eight of their last 10.
DeMarcus Cousins topped Sacramento with 24 points.
"I thought that we were awful tonight," Kings coach Michael Malone said. "The first and third quarter, I thought that our starting group was not ready to play. ... I am very disappointed with the effort tonight and we are nowhere near good enough to come into a playoff team's house and think we can go through the motions and try to turn it on when we want to.
"We are not that good a team."
The Raptors led for all but the game's opening two minutes and pulled away in the third quarter to take an 80-63 advantage into the fourth quarter.
Toronto led by as many as 23 points in the fourth. The Kings would cut that to 10 on Ben McLemore's 3-pointer with a minute to go that made the game seem closer than it was.
The first time the teams played last month in Sacramento -- a 109-101 Kings win that saw Sacramento lead by 20 going into the fourth -- was far too friendly for coach Dwane Casey's liking.
"I have friends who've been in this league 20-plus years, but I see them in the summertime," the Raptors coach said. "Guys were very professional, workmanlike, not disrespecting their friends on the other team, but knowing we had a job to do when you walk out between those lines.
"After the game is over you can shake hands, hug, kiss, whatever you want to do. But we have to have that razor-like focus every time we walk on the floor."
Salmons said the difference Friday was letting go "of the personal stuff."
"We said we were doing that the first game, but clearly we didn't," he said, "so it was time to just let it go and just play basketball. It was more professional this time around."
The Raptors were 6-12 when Raptors GM Masai Ujiri remade his roster, and Toronto has gone 28-14 since to sit third in the Eastern Conference.
Gay received a smattering of boos during the Kings' introductions, and again when he had Sacramento's first basket, but the level of hostility was nothing like that for former Raptors Vince Carter or even Andrea Bargnani when they played in Toronto.
The loudest jeers -- and cheers -- of the night came when Gay threw down a huge one-handed dunk but was called for traveling.
"Honestly, I didn't even pay attention to it," Gay said. "Boo or cheer, either way I have to go out and do my job."
Of the former Kings, Patterson had the strongest night against his former team, scoring on an array of shots, including a pretty put-back basket and huge alley-oop dunk in the fourth quarter that brought the crowd of 18,658 to its feet. He was 3-for-4 from 3-point range.
The Raptors shot 47 percent on the night to 42 for the Kings. The Raptors were the superior team from long range, shooting 10 for 21 from beyond the arc, while the Kings went just 5 for 19.
Toronto looked rejuvenated from a rare four days off without a game, racing out to an early eight-point lead in a foul-filled first quarter. The Raptors were up 29-19 going into the second.
The Raptors stretched their lead to 13 early in the second and then went cold, shooting 33 percent in the quarter and allowing the Kings to pull to within two points. Toronto took a 51-44 into the dressing room at halftime.
Ross scored nine points in the third, including a 3 with 3:13 left that put the Raptors up by 15, their biggest lead to that point. A layup by Patterson with 3 seconds left sent Toronto into the fourth quarter with an 80-63 advantage.
The Raptors are in Minnesota on Sunday and Brooklyn on Monday, then return to host Detroit on Wednesday. ... Toronto, which beat Golden State 104-98 last Sunday, hasn't dropped back-to-back home games since losing three straight in late November.