Chris Johnson's basket -- on an officials' reviewed goaltending call -- closed it to 93-90 with 1:49 left, but Lowry and Ross hit consecutive 3s on the next two possessions to send the Raptors to the victory.
In the third quarter, Lowry nailed consecutive 3s on Toronto's first two possessions, pushing the Raptors' lead to 61-46. They held at least a nine-point lead for the rest of the quarter, opening it to 77-62 after Ross nailed a 3 at the buzzer.
Toronto, which blew an 11-point second-quarter lead in less than 2 minutes, held a 55-46 advantage at halftime.
NOTES: A few minutes before the opening tip-off and about 10 after the National Anthems were completed, the Celtics asked the crowd to rise for a moment of silence to honor two Boston firefighters that were killed battling a fire in the city's Back Bay section -- about 2 miles away. ... Boston coach Brad Stevens praised Raptors G Lowry before the game. "(He) is playing terrific," Stevens said. "He was arguably an All-Star earlier. He makes a lot of plays that don't go talked about." ... Sullinger had 25 points and 20 rebounds when the Celtics beat the Raptors at home on Jan. 15. He had eight boards on Wednesday.
BOBCATS 116, NETS 111, OT: Al Jefferson scored 35 points, Kemba Walker had a double-double and the Charlotte Bobcats defeated the Brooklyn Nets for their 10th victory at home in the last 12 games.
Walker had 20 points and 12 assists and Chris Douglas-Roberts had 16 points, including two big jump shots in overtime.
It was Jefferson's 12th 30-point game this season for the Bobcats, who beat the Nets for only the second time in the last 11 meetings.
The win pulled the Bobcats within three games of the Nets, the fifth seed in the Eastern Conference. Charlotte (35-37) has the conference's seventh-best record.
Deron Williams finished with 29 points for Brooklyn, after scoring 18 in the first quarter. Joe Johnson had 18.
Josh McRoberts put the Bobcats ahead for good in overtime when he pulled off a reverse dunk in traffic.
SUNS 99, WIZARDS 93: After letting a 25-point lead dwindle to three, Suns guards Goran Dragic and Eric Bledsoe got back to business Wednesday night, combining to finish with 48 points, 13 assists and 13 rebounds, helping Phoenix earn its fifth consecutive victory.
The Suns moved into a tie with the Dallas Mavericks for the eighth and final playoff spot in the Western Conference. Both clubs are 43-29 with 10 games remaining.
The Suns have won seven of their last eight, coinciding with Bledsoe's return to the starting lineup after missing 2Â½ months because of knee surgery. He had 23 points, seven assists and six rebounds, and Dragic wound up with 25 points, six assists and seven rebounds.
John Wall led Washington with 29 points and six assists.
CAVALIERS 97, PISTONS 96: Dion Waiters hit a contested baseline jumper at the buzzer, completing a rally that lifted the Cleveland Cavaliers to a 97-96 victory over the Detroit Pistons on Wednesday night.
The Pistons led 82-66 going into the fourth quarter, but once again collapsed down the stretch.
Jarrett Jack hit a 3-pointer to pull the Cavaliers within 96-90 with 2:49 left, and his jump shot made it a 4-point game with 90 seconds to play. After a bad Brandon Jennings miss, Jack drove the lane and hit a floater while being fouled. His free throw made it 96-95 with 53.8 seconds left.
After several Piston misses and timeouts by both teams, Waiters got the ball in the right corner and hit a 19-footer as time expired.
Matt Dellavedova led Cleveland with a career-high 21 points, Waiters had 18 and Jack 17.
Josh Smith scored 24 points for Detroit.
CELTICS: Point guard Rajon Rondo has found a new way to stay busy when he's inactive for games this season: Color commentary.
Rondo, who is sitting out the second night of back-to-backs during his return from ACL surgery, will join Comcast SportsNet's Mike Gorman for the first quarter of Monday's game against the Chicago Bulls.
Comcast SportsNet has utilized a rotating cast of guest analysts during road games this season. Celtics president Danny Ainge also will serve as guest analyst for two games in April. Other guest analysts have included P.J. Carlesimo, Dave Cowens, and Cedric Maxwell (who will call the final three quarters of Monday's game after Rondo's visit). Former Celtics player Chris Herren will sit in as part of Ainge's broadcasts.
BULLS: Derrick Rose has been participating in non-contact drills in practice as he tries to work his way back from his second major knee injury.
Coach Tom Thibodeau also said Wednesday that the former MVP point guard will not play again this season, something the organization has said several times since he went down.
Rose tore the meniscus in his right knee at Portland in November and was ruled out for the remainder of the season by the Bulls. He sat out last year while recovering from surgery to repair a torn anterior cruciate ligament in his left knee.