The Raptors will try to record their second victory over the Pistons in four days Monday night and spoil Jose Calderon's return to Toronto.
The Raptors (27-46) have dropped six of seven but won 99-82 in Detroit on Friday. Rudy Gay scored 19 of his 21 points in the third quarter of that victory, and DeMar DeRozan and Amir Johnson contributed a combined 41 points.
Toronto, though, failed to build on that victory Sunday as it shot 39.5 percent in a 109-92 loss at Washington.
"I thought we came out with a relaxed disposition and didn't come out ready to go. The guys didn't look like they were ready to move their feet defensively," coach Dwane Casey said. "We had some frustration fouls, which kind of set the tone for the course of the game."
Foul trouble helped limit Gay to 11 points - seven below his season average - and DeRozan missed 12 of 18 shots while finishing with 15. DeRozan helped the Raptors shoot 53.7 percent in the win in Detroit.
"We've just got to be focused," DeRozan said. "We've got to understand we've only got so many games left. We've got to put our mind to it and play hard every game. It's as simple as that."
Also on Sunday, Detroit (24-50) suffered its 13th loss in 14 games, 95-94 in Chicago, after blowing an early 13-point lead. Rodney Stuckey had 25 points, his second-best scoring performance of the season.
Nine of the Pistons' previous 11 losses came by double digits.
"We have to take tonight - there were a lot of good things even though we lost - and build up and get ready for Toronto tomorrow," forward Greg Monroe said.
The Raptors will try to take advantage of the Pistons' woes to earn a series-best third straight home win. DeRozan scored 23 points and Alan Anderson had 12 of his 16 in the fourth quarter in a 97-91 victory over Detroit at the Air Canada Centre on Dec. 19.
Jose Calderon had 17 assists for Toronto, but now plays for Detroit after the three-team deal Jan. 30 that also sent Gay to the Raptors from Memphis. Calderon had eight points and seven assists Friday, his first game against the club with which he spent the first seven-and-a-half years of his career.
Monroe scored a career-high 35 points in the loss in December and has averaged 19.3 points and 11.4 rebounds in his last seven games in the series.
It's unclear if Pistons starting forward Jason Maxiell and reserve guard Will Bynum will be available. Maxiell stayed in Detroit over the weekend to get his eye examined and Bynum has missed the past three games with a hand injury.