Illawarra produced arguably their best three and half quarters under Justin Tatum to all but seal a stunning upset, only for the wheels to fall off down the stretch and leave them needing to pick up the pieces ahead of game two on Sunday.

The Hawks led 93-77 with just seven minutes left, only to be outscored 23-7 in regular time and allow the hosts to square the ledger with eight seconds left.

Even as the lead was whittled down, the Hawks found away to lead by two with 18 seconds left only for sub Kyle Adnam to turn the ball over on the inbound pass having seen less two minutes on the floor all night.

It allowed Chris Goulding to square the ledger in regulation, with United going 15-6 from there to seal the win, and the chance at a sweep in Wollongong having looked dead and buried midway through the final term.

It leaves Tatum facing the monumental task of picking up the pieces in time for Sunday's return clash in Wollongong, and ruing some highly questionable officiating that saw key calls go against the Hawks late in the piece.

Playing a lone hand for much of the contest, Matthew Dellevadova was outstanding for the hosts, finishing with 30 points at 6-10 from long range and 10 assists to get his team home.

Luke Travers was his primary support act with 24 points and eight rebounds, while Goulding (18 points), Ian Clark (14) and Shea Ili also cracked double digits in a memorable win for the regular season champs.

Sam Froling was monstrous for the Hawks with 26 points at 11-16, five rebounds and two assists, while Gary Clark had 22 points, 12 boards and three assists. However, both went cold when it mattered down the stretch.

"I felt that Melbourne turned the tempo up a little bit, they played with a sense of urgency the last seven minutes and it kind of threw us off," Tatum said post-game.

"Our tempo wasn't at the same pace that helped us get that 16-point lead.

"Them being at home and turning the tempo up a little bit, their pressure and the experience that they have, it kind of got away from us.

"This one is on me. My team understands that they've got to make sure that they find a way to pull the game out.

"You can't have a 17-point lead with any team and then allow them to come back, but I take this one on the chin as far as the preparation, the experience and getting them through this one.

"We'll be ready for the next one."

It could well be attributed to United's 17-day lay-off, but the Hawks got off to a flyer, leading from the jump largely on the back of Froling grabbing eight of his side's first 10 points.

Clark also had 13 in the opening term at 3-4 from long range, with the Hawks going 8-10 to start and finishing the term 11-17 as the visitors led 29-25 at the first break.

A 12-2 run saw the hosts re-take the lead and force Tatum into a timeout, but the Hawks responded with a 14-7 run to close the term, including a go-ahead three from Lee on the halftime buzzer.

Robinson relished his role as villain on the road with four points and six assists, with Dellevadova's 15 points at three of three from deep and five assists essentially keeping the hosts in the game.

A 13-1 run either side of halftime looked to have broken the game open for the visitors, and similarly hot start to the final term looked to have sealed the upset before the late-game yips hit.

It as heartbreaking as losses get, but Tatum said he won't be looking to re-invent the wheel on his team's return to Wollongong.

"It was working well, it wasn't broke," Tatum said.

"I think it's just playing up tempo type of basketball and being able to execute in the half-court and find our guys who are hot.

"We always want to push the tempo when we can and get easy shots in the transition, but we go to our guys, our bread and butter, when we go half-court.

"That's a different type of tempo, that's what it is, but we like a up tempo type of game. At the end of the day, we've just got to finish the game.

"Everything we did we were satisfied with, we just have to finish the games."

In Jo Lual Acuil and Ariel Hukporti, United have boasted a near unbeatable one-two punch inside but between the two of them, it took the best part of 40 minutes to find an answer for the Hawks skipper.

The longest tenured Hawk was locked in from the jump, grabbing eight of his team's first 10 points. It even prompted Vickerman to bench Lual Acuil and inject Hukporti in an effort to clamp down the Hawks co-skipper.

There was no keeping him out of the contest from there, his 26 points coming while keeping Lual Acuil and and Hukporti to a combined 14 points at 5-11 from the field.

They found an answer late, and Froling will need find a further gear, if it's there, to repeat the performance in Wollongong and keep his team's title hopes afloat.

While the Hawks were left ruing a series of self-inflicted wounds, there's no question the home side got the rub of the green on several key calls late in the contest.

Crucially, Justin Robinson was called for an offensive foul off the ball on Goulding that both live callers Derek Rucker and Andrew Gaze labelled plainly incorrect with 1.14 left in the fourth quarter.

The pair of basketball greats were also bemused when Lual Acuil wasn't called for a foul for blatantly holding Clark in a tussle for an inbound play with 18 seconds left.

Likewise on the final turnover Dellevadova looked to have hold of Robinson's singlet as he attempted to catch Adnam's inbound. It didn't cost the Hawks the game, but did not go unnoticed.

"One hundred per cent," Tatum said when asked if the officiating changed in the fourth quarter.

"I don't know what they're reviewing when JL A and Gary get mixed up on trying the long inbound pass and you see [Lual Acuil's] whole arm wrapped around [Clark] and we're looking at who took the ball out of bounds?

"Then we're trying to get the ball inbounds and J-Rob's getting grabbed in the corner by Dellevadova. This is playoffs and I thought we had the best officiating crew. That's what we were supposed to have and what we were told, but it is what it is.

"People they got out there have got to do their job and call the obvious things. I'm not blaming them for a loss, just some of the inconsistencies that helped them to it.

"We were fighting other things out there as well, so it is what it is."

Injury replacement Adnam has played less than five minutes total since being brought in as a replacement for Dan Grida, but he was injected with 23 seconds left and given inbounding responsibilities.

It resulted in a turnover on the inbound pass with 18 seconds left with the Hawks leading 100-98. Goulding took advantage at the other end, a lay-up levelling the scores at 100 apiece with four seconds left.

The Hawks advanced on a timeout, but had sharpshooter Harvey inbound the ball with Robinson's last ditch hoist at a go-ahead basket not going close and sending the game to overtime.

Having played less than 90 seconds before checking into the game late, it was a call that both Rucker and Gaze questioned live, and one that will no doubt attract scrutiny in the wash-up.

"His experience, his composure and his free throw making ability," Tatum said when asked why he injected Adnam when he did.

"They had four fouls to get until they were in the bonus, so we wanted to make sure that we had some of our most solid and most best decision makers in the game."