Trailing 2-1 in the best-of-five series, United held their nerve at Hobart's MyState Bank Arena on Thursday night with Matthew Dellavedova sinking the deciding shot with 7.2 seconds on the clock.

Dellavedova, a 2016 NBA champion with Cleveland, nailed a lay-up to put Melbourne ahead 87-86.

Tasmania had a possession on the attack in the dying seconds but turned the ball over with United's Ian Clark getting to the free-throw line to seal the deal.

Jack McViegh threw a last-gasp Hail Mary from outside the three-point line for the JackJumpers but couldn't repeat his heroics from game three.

"We had a great belief that we were just going to win this one," Melbourne coach Dean Vickerman said.

"There were some amazing desperation plays ... our ability to dive on the floor and come up with extra possessions."

The fifth and deciding game will be held at Melbourne's John Cain Arena on Sunday afternoon.

Tasmania are gunning for their maiden title in just their third season, while United are chasing their second championship success in four competitions.

"Our guys will be up. No one expects us to be sitting here to begin with ... now we're here again," JackJumpers coach Scott Roth said.

"We earned the right to get to game five because we won on their floor (in game three)."

Clark top-scored for Melbourne with 18 points, while Luke Travers had a lively game with a game-high 11 rebounds and 17 points.

McVeigh was immense for Tasmania with 28 points and seven rebounds after his match-winning effort from beyond the three-point line in game three.

Melbourne took a 67-66 lead into the final quarter in a game where neither side was able to pull away.

Roth had a crack at the officials after losing a coach's challenge following a foul call on Anthony Drmic.

"I just make coaches challenges out of the blue, because I have no idea what they call anyway," he said.

"I just throw it on the wall and see if it sticks.

"Obviously from our perspective (it should have been overturned). There are other ones where ... all of a sudden we've won it. I've got zero clue."

Both teams were sloppy in a frantic first term in which Melbourne were just 30 per cent from the field.

Tasmania had a 20-17 lead at quarter time but found themselves behind when Melbourne went on a nine-point run early in the second.

JackJumpers' import Jordon Crawford sunk a three to end United's run before the hosts went on a 10-point run of their own.

McVeigh started strongly and had 18 points by halftime, while teammate Milton Doyle came to life early in the third after a scoreless two quarters.

In a tit-for-tat third period, United's Chris Goulding hit crucial back-to-back threes to level at 55-55.

Australian Associated Press