Roy rebounded from his cold spell to hit a 22-foot jumper with 0.9 seconds left that gave the Portland Trail Blazers a 76-74 victory Friday night.
"I was just laughing like, `Finally, I made a shot," Roy said. "And it was the one that helped us win an important game for us."
Afterward, Roy ran over to the bench and chest-bumped fellow guard Jerryd Bayless.
Roy, who averaged 27 points last week as the Western Conference player of the week, finished with 14 points to help the Blazers win their fifth straight game.
Nicolas Batum hit free throws before Foye hit another jumper that made it 74-72 for Washington 1:01 left.
"I played so bad it was like when I made it, it wasn't, `Yeah! Another game winner,' it was like `Finally, I made a shot," Roy said.
Aldridge had 19 points and 12 rebounds for the Blazers, and Miller added 14 points. Marcus Camby had 19 rebounds.
But the Blazers made just 25 of 78 field goals, or 32.1 percent -- an all-time franchise low. Roy was 4 for 18 from the floor.
"A struggling player that's a great player is going to find a way to push through and make that last shot, and that's what he did," Washington's James Singleton said.
Portland appeared inexplicably sluggish after a rare four days off following a 109-98 victory over Toronto on Sunday.
Miller's fadeaway jumper put Portland up 36-26 and the Blazers led 16 points en route to a 42-30 halftime lead. Roy had 10 first-half points and Camby had 11 first-half rebounds.
But the Blazers struggled in the third quarter, shooting just 19 percent from the floor. As Roy's misses mounted to 12 straight, the Wizards closed to 55-51 on Singleton's layup to start the fourth quarter.
Earlier Friday the Wizards signed guard Shaun Livingston for the rest of the season after playing through a pair of 10-day contracts. He originally joined Washington on Feb. 26.
Going into the game, he averaged 4.9 points and 3.3 assists in 15 1/2 minutes in 10 games. He scored Washington's first basket against the Blazers.
Earl Boykins did not make the trip to Portland with the Wizards because of a stomach virus.
Blatche started despite spraining his left ankle in practice on Tuesday and finished with 12 points.
Singleton added 10 points and a career-high 16 rebounds.
"It's always the ones you fight back from that hurt the worst," he said. "But I'm happy with the effort we put into the game tonight."
Roy arrived at the arena dressed in his University of Washington warmups. Roy wore No. 3 for the Huskies and is unabashedly rooting for them in the NCAA tournament. Washington will play New Mexico in a second-round game in San Jose on Saturday. ... Portland's Andre Miller played in his 600th consecutive game -- the longest active streak in the NBA -- on his birthday. ... Portland's 76 points were the fewest in a victory since a 76-75 victory against Houston on April 5, 2006. ... The Wizards matched their season low for points scored.