Lowry scored 17 of his 21 points in the fourth quarter to lead Toronto to a 91-86 comeback victory over the Philadelphia 76ers on Friday night.
"I'm glad we came back, but we can't rely on that if we are serious about competing in this league," Casey said. "We've got an air of complacency and I don't like it. It's everybody collectively. We have to come out with a better effort. We can't come out and perform like that."
It was just the fourth win in the last 12 games for the Atlantic Division-leading Raptors, who gave up the first 15 points, trailed by as many as 16 early and had to overcome a nine-point deficit with 5 1/2 minutes remaining against the hapless 76ers.
"I feel like we need every win we can get," Lowry said. "We can't let games like this slip away from us. That's a hard-playing team, but we have a bigger goal."
Patrick Patterson added 14 points and 13 rebounds for the Raptors.
Lowry, selected Thursday as a starter for the All-Star game, entered the final period with four points on 2-for-9 shooting before heating up late when the Raptors desperately needed him.
Robert Covington scored 18 points to lead six 76ers in double-figures. It was the fourth straight loss and sixth in seven games for Philadelphia, which dropped to 3-18 at home.
Philadelphia played without leading scorer Tony Wroten for the sixth straight contest. The team announced before the game that Wroten will be sidelined indefinitely due to a partially torn ACL that will require surgery.
Philadelphia's Nerlens Noel returned to the lineup after missing Wednesday's 98-91 loss to the Knicks due to sickness. It was the first time Noel and Michael Carter-Williams were on the court together since Noel's critical comments of the Philadelphia point guard following Monday's 111-76 defeat at Washington.
The duo provided a Philadelphia highlight early in the fourth quarter when Carter-Williams whipped an over-the-shoulder pass to Noel for an easy dunk that tied the game at 68 with 9:09 left.
The 76ers then went ahead 70-68 on Luc Mbah a Moute's jumper with 8:11 remaining, giving Philadelphia its first lead since early in the second quarter. Two straight baskets by Noel followed by Mbah a Moute's three-point play put Philadelphia up 77-69 with 5:39 to play.
Lowry, a Philadelphia native, then heated up, scoring all 13 points during a 13-4 Toronto run over the next three minutes and his third 3-pointer during the stretch knotted the game at 81 with 2:48 left.
"I just didn't want us to lose tonight," Lowry said. "I think my teammates were counting on me and we needed somebody to pick up the energy. And I felt like it was my time to pick up the energy and go out there and do my job."
The Raptors went up 85-81 on Demar DeRozan's layup and Lowry's two free throws, but Carter-Williams hit a 3 with 1:03 left and then stripped Lowry and converted a breakaway layup to give the 76ers an 86-85 lead with 42.1 seconds left.
Greivis Vasquez put Toronto back in front 87-86 with a layup with 25.9 seconds remaining.
The 76ers had a chance to go in front, but Carter-Williams' pass attempt inside to Noels was denied. He then committed a foul and Jonas Valanciunas made both free throws with 10.6 seconds left, and Philadelphia couldn't convert on its possession.
As they've done all season, Philadelphia remained positive with a long-term look at yet another defeat.
"Games like that go a long way for us as a young team," Noel said. "And as we continue to grow and be in certain situations like that, we'll only get better with our defensive and offensive execution and just being able to close out games like that."
Noel finished with 12 points and a career-high 14 rebounds, giving him six double-doubles on the season. That marks the most among rookies.
HOLD THEM DOWN
Toronto improved to 9-0 this season when holding teams under 90 points and have won 18 straight dating to last season when keeping opponents under that mark.
Raptors: Lowry is the third Raptors player to earn an All-Star game start, joining Chris Bosh (2007) and Vince Carter (2000-04). ... Toronto won its seventh straight against Philadelphia, including three this season.
76ers: Mbah a Moute returned to the lineup after missing the last two games with a left knee injury. ... Philadelphia failed to reach 100 points for the 20th consecutive game, marking the longest such streak for the club since doing it 25 straight times in the 2003-04 season.
The 76ers visit Memphis on Saturday night.
Toronto hosts Detroit on Sunday.