The Wizards were handed their 62nd loss, one short of the franchise record, when Chris Bosh made the go-ahead 3-pointer with 9.9 seconds left Monday night in the Raptors' 97-96 victory.
The Wizards must win their final game on Wednesday in Boston to avoid tying the 2000-01 team with a 19-63 mark.
For interim coach Ed Tapscott, who's had to endure lots of speculation that he's about to be replaced by former Minnesota and Detroit coach Flip Saunders, it was simple.
"We brainlocked," Tapscott said.
"We made just about every error you could make going down the stretch of a game."
Trailing 93-80 with 6:30 remaining, Toronto outscored Washington 17-3 to pull off the win.
The Wizards seemed to have the game in hand after Brendan Haywood blocked two shots in the final moments, and hit one of two free throws with 26 seconds remaining to give Washington a 96-92 lead.
Shawn Marion's layup with 21 seconds left made it 96-94, and with Tapscott trying frantically to call timeout, the Wizards' Juan Dixon threw an upcourt pass out of bounds to give the Raptors the opportunity for the game-winner.
During the timeout, Tapscott implored his players not to give any open 3s, but they didn't listen.
Bosh, who had 25 points and 15 rebounds, converted his first 3-pointer since March 6.
"I took my time, thought about it, spun the ball, thought about it some more, practiced my release first and then let it go," Bosh said. "It went in, I'm happy ... go for the kill, why not."
He had his 42nd double-double of the season, tying his 2006-07 franchise high. Marion had 25 points and 15 rebounds.
Caron Butler scored 28 points and Antawn Jamison had 23. Butler, who gave Washington a 93-80 lead when he hit two free throws with 6:30 to play, missed all four of his shots in the fourth quarter. The final was when his layup attempt was smothered with 0.1 seconds to play.
"We fought tonight. We didn't think tonight," Tapscott said.
Butler was double-teamed for much of the final quarter after Jamison hobbled off the court with a right ankle injury early in the quarter.
He's eager for this nightmare season to end.
"You never want to feel like this again," Butler said. "You don't want to be associated with not making the playoffs -- with the worst record in franchise history."
Washington played without Gilbert Arenas, who's played just twice in his on-again, off-again rehab stint from left knee surgery. Tapscott didn't sound hopeful that Arenas would play on Wednesday.
"We only have one game left," Tapscott said. "I don't want to rule it out. I don't want to rule it in."
Toronto was without center Andrea Bargnani, who's been hampered by a sore left heel. Bargnani played the Raptors' final home game of the season on Sunday against Philadelphia, but interim coach Jay Triano wouldn't play him on consecutive days.
"We know he's playing through pain. Back-to-backs are out of the question," Triano said.
Bargnani could play in Toronto's final game in Chicago on Wednesday.
Tapscott tried to deflect talk that he would be replaced by Saunders after the season. "It's just best that I not comment on that," Tapscott said. "For me, it's just a matter of focusing on finishing the season as strongly as possible." ... The Raptors signed G Quincy Douby for the rest of the season and for the 2009-10 season. ... Washington was without F Andray Blatche, who was sidelined with a sore left knee.