BOSTON -- The Boston Celtics ensured their first winning season in three years under Brad Stevens on Wednesday night, taking advantage of the surprise absence of Toronto floor leader Kyle Lowry to earn a 91-79 victory over the Raptors.

However, being 42-30 is nothing for Stevens to be excited about, which he made clear after his team's third win in four nights.

"There's been good progress and good growth in our team, and that's my biggest focus," Stevens said. "(But) you don't sign up to come to the Boston Celtics to win 42 games.

"We've got a long way to go."

And that long way begins with a five-game Western trip that starts in Phoenix on Friday night. Before leaving, though, the Celtics cashed in on Toronto having no Lowry (elbow) and Patrick Patterson (ankle) and salvaged the fourth game of the season series with the Raptors.

"We told each other we needed to get these three wins in a row to build momentum to go out against Phoenix and take care of the same thing," said Boston guard Avery Bradley, who had 16 points and eight rebounds.

With Lowry a late scratch due to a sore right elbow, the Celtics built an 11-point lead late in the third quarter and then overcame their own scoreless run that lasted over six minutes.

Isaiah Thomas hit a 3-pointer, set up Amir Johnson for a slam and then hit another trey to turn a one-point game into a seven-point Celtics lead.

The loss, which ended Toronto's four-game winning streak, kept the Raptors from breaking their team record for victories -- they have won 48 games each of the past three seasons. However, the Raptors clinched a playoff berth with the Chicago Bulls losing.

"It's always good to get into the playoffs," said Toronto coach Dwane Casey, whose team fell to 48-22. "I know that feeling of going home and sitting and watching everybody play. When you have something to look forward to, the next couple of weeks, that's what we realize, we have to tighten this thing up for the real thing."

In addition to missing Lowry, who is averaging 21.9 points, 6.4 assists and five rebounds per game, the Raptors were also without valuable part Patterson.

"Day and night. Day and night," Casey said. "I think any team when they have guys out, there's going to be some type of difference. We've just got to get accustomed the next couple of weeks with guys out with rest or injured."

Evan Turner scored 13 of his 17 points in the third quarter as the Celtics, 16-2 in their past 18 home games, took a 69-58 lead with 2:14 left in the period. However, Boston's next points didn't come until Marcus Smart scored his only basket with 7:49 left in the game. The Raptors scored 10 points during that time but also missed six free throws en route to going 11-for-20 on the night.

Thomas continued his offensive tear, scoring his team's first seven points and finishing with 23 points -- his 11th consecutive 20-point game. Turner added seven assists, four rebounds and two blocked shots. Johnson, a former Raptor, scored 11 points, grabbed 14 rebounds, dished out five assists and blocked two shots in his second straight double-double, his seventh of the season. Jared Sullinger had nine points and 11 rebounds.

DeMar DeRozan led the Raptors with 21 points. Terrence Ross had 13 points, and Jonas Valanciunas scored 10. Bismack Biyombo had zero points and 13 rebounds, and Jason Thompson finished with 10 rebounds and six points.

Without Lowry, who had 32 points against the Celtics in a win last Friday, the Raptors finished 24 points under their season scoring average. The loss dropped Toronto 2 1/2 games behind the Cleveland Cavaliers, who won Wednesday, in the race for the best record in the Eastern Conference.

The Celtics kept pace in their battle for the third spot in the conference.

NOTES: Corey Joseph started in place of PG Kyle Lowry after resting in the previous game. He finished with nine points and four assists. ... Before the Lowry news, Toronto coach Dwane Casey said his team's health is more important than making up their deficit and catching the Cleveland Cavaliers for the Eastern Conference's top seed. The players seem to feel the same way, noting they would have home court for all rounds except the conference finals. ... Raptors C Jonas Valanciunas returned after missing four games with a hand contusion, started and had 10 points and seven rebounds. ... Celtics F Jae Crowder missed his sixth straight game with a high ankle sprain, but the hope is that he can return at some point during the upcoming five-game trip. ... The Celtics observed a moment of silence for the victims of the Brussels tragedy.