01/08/2014 09:52 EST | Updated 03/10/2014 05:59 EDT

Valanciunas has 16 points, 11 rebounds as Raptors beat Pistons 112-91

TORONTO - A half-time message woke up the Raptors on a night when Toronto found itself sleepwalking against the struggling Detroit Pistons.

"We pretty much said, 'This is a must-win game,'" Amir Johnson said after Toronto trailed Detroit by four at the break but finished with a 112-91 win Wednesday.

"We had to go out and take it. We did that."

After Johnson and DeMar DeRozan started the game cold, their teammates kept things close and allowed a second-half turnaround to take place.

Jonas Valanciunas had 16 points and 11 rebounds while Kyle Lowry scored 21 points and added nine assists in a game the Raptors needed to work themselves into.

"The first half was a little sluggish but we picked it up and that's most important," said Lowry. "That's a team. You need everybody, all 15 guys and all 13 that are dressed to step up and take advantage when the opportunity comes."

Toronto (17-17) needed strong performances from Valanciunas and Lowry. DeRozan and Johnson combined to shoot 0 for 16 from the floor in the first half with the team making just 33 per cent of their field goals compared to 47 per cent shooting from the Pistons.

Brandon Jennings led the way for Detroit (14-22), scoring 22 points to go with nine assists in the loss. Andre Drummond added 16 rebounds as the Pistons lost their sixth straight.

After going up 11 midway through the second quarter, the Raptors went more than five minutes without a field goal and allowed Detroit to go on a 14-0 run to take a 54-50 lead at the half.

"We started off terrible," DeRozan said. "We didn't have any legs and we told ourselves that we can have no excuses. We had to pick it up because that wasn't us in the first half."

Things flipped in the third quarter when the Raptors outscored Detroit 34-20 while making 11 of their 22 field-goal attempts. DeRozan and Johnson were able to shake off their starts to help Toronto build a 10-point advantage going into the fourth.

"There was a big difference," Toronto head coach Dwane Casey said of the two halves. "We knew it was going to be a grind out game and that's something we are learning to do, to grind things out possession by possession, quarter by quarter.

"We knew DeMar and Amir weren't going to go zero-for, in the second half. The defensive intensity (after halftime) is what changed the game."

The final quarter resembled the third as Toronto outplayed the Pistons and broke the game open with five minutes remaining and the lead up to 18. All five of Toronto's starters finished the game in double figures after the team dropped its last two contests against the Miami Heat and Indiana Pacers.

DeRozan finished the game shooting just 3 for 15 from the floor, but connected on 13 of his 16 free-throw attempts to finish the game with 19 points. The 16 free throws tied a career-high.

"He went to plan B and that's what he's got to do," Casey said about DeRozan's night. "About a year or two ago he wouldn't have done that. He did a good job of attacking the feet and taking what the defence gave him."

Johnson finished the game with 10 points and 11 rebounds and Terrance Ross scored 17 points.

"He's improving as a basketball player," Lowry said of Ross's evolving game. "Catching and shooting, his confidence is unbelievable. He's showing his versatility. He can play defence. He's scoring, but if you look at the defensive assignments he's had in the past few weeks, he's done a great job at it ... I know I tip my hat to him."

Lowry's explanation for the strides Ross has taken was simple — he's playing more.

"That's how you get better," he said. "Once you get more minutes, more repetition, that's how you get better."

Toronto finished the game shooting 41 per cent from the floor as compared to 40 per cent for the Pistons, but the Raptors shot 91 per cent from the free-throw line, making 31 of their 34 attempts. Detroit made just 19-for-35 shots from the line.

Notes: Toronto's Tyler Hansbrough missed his fourth straight game with a left ankle sprain. ... Rodney Stuckey returned to action for the Pistons after missing three games with a sore shoulder. ... The Raptors return to the court Saturday at home to the Brooklyn Nets.