Toronto, however, was ready with the counter-punch.
Reserve Linas Kleiza scored a season-high 25 points, including four of the Raptors' 10 three-pointers, and Toronto rallied for a 111-106 victory in double-overtime for its first win in Utah since 2004.
"It was huge," Casey said. "Our guys came out and battled after the first quarter. Linas really battled and got us back into the game. "
Jose Calderon hit a three-pointer to tie it at the end of regulation and Andrea Bargnani poured in 25 points on 10-of-26 shooting for the Raptors.
On the downside, Bargnani reinjured his strained left calf late and wasn't optimistic.
"This time it's bad," said Bargnani, who planned to undergo an MRI. "I'm pretty sure I'm going to be out for a while."
Bargnani had just returned Tuesday night after missing six games with the calf injury. He scored 36 points in a 99-96 win over Phoenix on Tuesday night, which ended an eight-game losing streak against the Suns.
The Raptors followed that by halting their 11-game skid against the Jazz.
"It's tough," said Utah guard Raja Bell, who scored 11 points. "We had opportunities. We were right there despite some of the mistakes we made. We were in it. You just have to keep fighting in a game like this and hope you might get it out at the end. They were the better team tonight so they deserved it."
Paul Millsap led Utah with a season-high 31 points, including a three-pointer to force the second overtime. Devin Harris added a season-best 24 points for the Jazz, but missed three late free throws.
Utah centre Al Jefferson sat out because of an inflamed right ankle and was wearing a walking boot on the sideline.
The Jazz got off to a great start, hitting eight of their first 12 shots, but they finished shooting just 43.3 per cent (39 of 90). Their free-throw shooting was worse, making just 24 of 36.
Toronto scored the first five points of overtime on a layup from Calderon and Kleiza's three-pointer.
Derrick Favors' jam off a Gordon Hayward steal pulled Utah to 95-93, and Millsap tipped in Hayward's airball with 1:13 left to tie the game at 95.
Kleiza hit his fourth three-pointer to bump Toronto's lead to 98-95.
Millsap's free throws made it a one-point game with 43 seconds left in OT, but Kleiza hit a pair of free throws to push it to 100-97 with 52 seconds left, setting up Millsap's tying three at the end of the first extra period.
Kleiza hit a 21-footer in the second OT and Calderon added a three-pointer to put Toronto up 109-103.
Harris made only one of four free throws down the stretch, and the Raptors sealed it on a jumper by Leandro Barbosa.
"We got away from playing good hard-nosed defence," Millsap said. "We got a lot of early shots off our defence. You need to give Toronto credit. They fought hard and hung in and hit some big shots down the stretch."
The loss was only the third for Utah at home this season.
The Jazz led by as many as 18 points in the first quarter, fuelled by Harris, who had 12 points and a four-point play on a shot that banked in with 8:16 left.
The Raptors cut the gap to 32-23 at the end of one, with Barbosa hitting his first three shots, Bargnani draining a three-pointer and Amir Johnson scoring on a driving layup.
Toronto opened the second quarter on a 6-0 run to pull to 34-29 and was within two on Kleiza's three-pointer with 6:23 left in the half. Bargnani's three-pointer with 55 seconds left in the half gave the Raptors their first lead at 50-48.
After shooting 67 per cent to open the game, the Jazz missed 18 of their next 28 shots and were at 42.1 per cent at halftime.
It didn't help that Utah was without Jefferson, who leads the team in scoring (18.3) and rebounding (9.4). He missed one game earlier this season with the same injury.
Second-year pro Favors started in Jefferson's place but got into early foul trouble, picking up his second with 3:34 left in the first. He finished with 16 points and 12 rebounds.
Notes: Jazz swingman Josh Howard returned to action after missing four games with a left quad strain. He started 0 of 4 and finished with no points. ... The Jazz held a 14-2 edge in fast-break points in the first quarter. ... Toronto had not scored over 100 points since an opening-night win over Cleveland. ... Kleiza's career-high of 41 points also came against the Jazz as a member of the Nuggets in 2008.