CLEVELAND — Leprechauns are imaginary. Celtic pride is very real.

Avery Bradley’s 3-pointer danced on the rim and dropped with less than a second left and Boston, blown out in the first two games of the Eastern Conference finals and playing without star Isaiah Thomas, stunned the Cleveland Cavaliers 111-108 on Sunday night in Game 3 to end the champions’ 13-game postseason winning streak.

Bradley’s shot from the left wing — off a play designed by coach Brad Stevens — bounced on the rim four times before going down. It capped a furious, focused comeback by the Celtics, who trailed by 21 in the third quarter before rallying to tighten up a series that appeared to be over.

“We have guys who have chips on their shoulders,” Boston coach Brad Stevens said. “We knew that Friday (Game 2) was a disaster. It wasn’t worth all four. It was worth one. So we got back together.”

Smart, who started in place of Thomas, made seven 3-pointers and scored 27 points, and Bradley had 20 for the Celtics, who were given little chance after losing by 44 in Game 2 and then losing Thomas for the rest of the postseason because of a hip injury.

“Everybody had to step up their game tonight especially with one of our brothers down,” Smart said. “Our love and support goes out to Isaiah. We wish he could be here but we understand. We just kept fighting.”

Kyrie Irving scored 29 points, and Kevin Love had 28 for Cleveland. The Cavaliers dropped to 10-1 in the postseason with their first loss since Game 4 of last year’s Finals.

LeBron James had one of the worst games of his postseason career, finishing with 11 points and six turnovers. On his way to the postgame news conference, the superstar got into an exchange with a fan who heckled him.