The All-Star hit a three-pointer with 3.5 seconds left over Celtics guard Avery Bradley to give Washington a 92-91 victory, forcing this Eastern Conference semifinal series to a Game 7.
Wall's turnovers have come down considerably over the past two games after he committed seven in Game 4, a 121-102 win for the Wizards at Verizon Center. Wall sank the game-winning 3-point shot.
The Wizards own one of these road wins. "It just happens. I don't really know the real reason".
"Not too many guys can do that", Washington coach Scott Brooks said.
Thomas and Avery Bradley had 27 apiece for the Celtics, while the Wizards were led by 33 points from Bradley Beal and 26 from Wall. "A guy like John Wall you're not gonna stop.He does a hell of a job on him". Tip-off is scheduled for 8 p.m. ET. The victor will face LeBron James and the Cleveland Cavaliers in the East finals starting Wednesday.
The host has won all 10 games between the Wizards and Celtics this season - four in the regular season and six in the playoffs. "Seems like it was meant to be".More news: New Orleans removes 2nd of 4 Confederate statues before dawn
"I'm proud of him", Thomas said.
Like the rest of his teammates, he was left to get back into his dark outfit afterward.
"Don't come to my city, wearing all black, talking about it's a funeral", Wall told ESPN after the win.
"The action is pretty even for side bets; however, 60 percent of the parlays include the Celtics +5", GTBets' lines manager said. "They should have been motivated by everything else".
Bradley was just about as locked in as he was in Game 5, scoring 27 points on 10-of-18 shooting for Boston.
In a tightly contested final quarter with nine lead changes, the Wizards responded with the best defense and the biggest shots.More news: Pentagon chief, Turkish PM meet after decision to arm Kurds
Thomas momentarily took the game over when it was tied 82-82 with five straight points, which gave Boston an 87-82 advantage with 1:34 remaining.
Al Horford banked in a 16-foot jumper with 7.7 seconds to play to snap an 89-89 tie, but it only set up Wall's heroics.
"We definitely want to finish it tonight", said Isaiah Thomas. John Wall will make a couple fantastic plays, bench fodder like Kelly Oubre will make a couple 3's, and the Celtics will fold up shop and start focusing on Game 7. The Wizards as a whole started 1 for 15 from beyond the arc.
"I had nowhere to go. We have nothing to hold our heads down about, we're going to take a few days to figure out our adjustments and win Game 7".
Celtics: Their 42-41 halftime lead was the visitors' first since edge since 2-0 on Horford's basket. Trying to reach the East finals for the first time since 2012.
Thomas and the Celtics let a chance to close the series slip away Friday night. This was the first win by a home team facing elimination on its court in these National Basketball Association playoffs; hosts had been 0-10 in that situation until Friday. "We don't like them, they don't like us", said the Celtics' 28-year-old guard Isaiah Thomas after Game 3, a 116-89 beatdown by the Wizards. Joked Brooks on Thursday: "I'll take a 25-point run. Makes me look thin, right?"More news: These Are the Richest Rappers in the World