McVeigh put up a prayer from well behind the three-point line after Matthew Dellavedova turned over an in-bounds pass with just seconds left.

The shot rattled in, sparking wild scenes among the travelling contingent of JackJumpers fans in the 10,175-strong crowd at a sold-out John Cain Arena on Sunday.

The lead changed hands seven times in a frantic last three-and-a-half minutes before McVeigh settled a gripping contest from near half-court.

"Our guys were very gritty at the right times and kept competing and found ways," Tasmania coach Scott Roth said.

"It was a hell of a shot that Jack made and I feel for them (Melbourne) over there because I've lost games just like that when you think you have it.

"But our determination and grit was on display and the fight was really good."

Tasmania lead 2-1 in the best-of-five series, which returns to Hobart for game four on Thursday night.

If required, game five will be played in Melbourne next Sunday.

McVeigh finished with 18 points and 12 rebounds in a huge game-three performance that included eight offensive boards.

Majok Deng (15 points) was also vital when called on to step up off the bench after import centre Marcus Lee limped off with a leg injury during the third quarter.

Roth's small-ball line-up did the trick, with Deng as his five-man, while Jordon Crawford and Milton Doyle finished 14 points each.

Doyle, who was in foul trouble throughout the game, saved Dellavedova's wayward in-bounds pass from going out in a crucial decision that led to McVeigh's game-winner.

"I saw Sean (Macdonald) jump and I couldn't tell if he touched it or not, but I wasn't going to leave it up to the refs to make a decision," Doyle said.

"I saved it in, I looked and I saw Jack and we just got him the ball.

"I knew whoever got it could make a play with six seconds left on the clock."

Dellavedova (21 points) and captain Chris Goulding (17) led Melbourne's scoring, while Luke Travers (14 points, eight rebounds, four blocks) had an influence at both ends of the floor.

Melbourne allowed the JackJumpers to pull down 21 offensive rebounds to their 10 and the visitors landed 16-of-33 three-point attempts.

"That's what they've done all year and it was a massive factor in the game," United coach Dean Vickerman said.

"The two areas that you need to be good against this team is how you box out and how you guard the three-point line, and we weren't good enough in either of those two."

Veteran guard Dellavedova was left "very disappointed and frustrated" by the defeat and took some of the blame.

"(It was) obviously a bad pass, Jack hits a big shot, but now we've just got to recover and focus to see what we can do better down there (in Hobart)," Dellavedova said.

Lee was hurt when teammate Crawford fell and collided with his left leg, leaving the big man on the floor in pain.

Lee has not yet been ruled out for the rest of the series and faces further assessment on Monday when the JackJumpers return to Hobart.

Australian Associated Press