A bumper crowd saw cards, goals and an unending display of skill as the visitors took the lead after just 6? minutes in their first meaningful foray forward, as Damon Collina found the back of the net with a sweet header from a right-sided cross.
If the Sharks were shell-shocked it didn?t show, although United could have made it two in two minutes when Ben Vidaic was put clean through but screwed his cross-shot effort wide of the far post before the home team levelled the match.
Shane Lyons showed great tenacity in winning the ball near the corner touchline and pulling the ball back to Jim Bakis.
He neatly sidestepped a United defender and in almost the same movement sent a curling shot into the top left hand corner despite the despairing efforts of ?keeper Vedran Janjetovic.
Glavas was not to be denied and a second goal for United came 10? minutes later when his shot bewildered Phillip Zabaks after a pinpoint through ball from Saso Trajcevski dissected the Sharks defence.
The resilience of the Sharks was clear to see as they countered with a second equaliser in the 23? minute after a scramble in the box saw the ball fall to Ben Spruce who made no mistake from close-range.
At the break the tie remained all square.
What the match was crying out for was for someone to put their foot on the ball in midfield, slow it down and take control but for the bumper crowd it was pure entertainment.
United began the second-half brightly and with a little more luck could have held the lead for the third time but for the header of Joe Moric flashing just wide.
However it was the home side who went ahead for the first time moments later as Bakic provided the cross from the right to the back post where Brendan Gan ghosted in to neatly head home.
Andrija Petkovic saw his curling free-kick barely curl over the bar from 20-yards out when the ball just wouldn?t dip in time to level it all up once more before the match became a real arm wrestle.
Michael Katz perhaps should have extended the Sharks lead in the 68? minute after sprinting away down the right.
As he shaped to cross it was apparent no United defender was coming to him so he took the ball on and fired in a cracking low shot, but Janjetovic was down smartly at the base of his left-hand upright.
Not long after and everything could have gone pear shaped for the Sharks when Nick Stavroulakis was sent-off for a tackle on substitute Mitchell Thompson.
Another substitute, this time for the Sharks, in the shape of Mike Robinson saw the 10-men seal the match.
Robinson played a couple of neat passes with Michael Katz to send the right back clear.
Evading a couple of tackles in the box and a thunderous right-footer under the dive of Janjetovic and the comeback was complete.
Vidaic could have made the dying moments a very nervous time for the Sharks but although his shot had the power it lacked accuracy and went close but wide.
Brian Brown, Sharks coach, said after the game: ?I?m obviously very happy with the result but I feel we let in two silly goals.
?It was another tough game but you expect that in this league although there were times tonight when our football was outstanding. The passing, fluidity and control we showed in patches were good signs.?
A spokesperson for United said: ?We gave away a silly goal to let them back in and gifted them another.
?Some of their younger players were very good this evening although perhaps we could have got and maybe deserved something from the game.?
It was a match where one unbeaten side was always likely to surrender the name and on this occasion it was Sydney United in 90-minutes of non-stop action that really could have gone either way.
The down side for the Sharks was Brad Boardman being substituted with a rib injury midway through the second period. The striker was taken to hospital for x-rays after the whistle.
Sutherland Sharks 4 (Jim Bakis 10?, Ben Spruce 26?, Brendan Gan 48?, Michael Katz 81?)
Sydney United 2 (Damon Collina 6?, Luka Glavas 20?)
Venue: Seymour Shaw Park
Referee: Peter Vrtkovski
Sutherland Sharks: 99. Phillip Zabaks, 15. Michael Katz, 2. George Souris (38. Mike Robinson 61?), 11. Ben Spruce, 8. David Huxley, 3. Brendan Gan, 7. Jim Bakis, 4. Predrag Bojic, 14. Nick Stavroulakis, 6. Shane Lyons, 9. Brad Boardman (David Reid 75?)
Substitutes not used: 1. Michael Brandalise, 10. Matthew Hall, 20. James Lawrence
Yellow Cards: 3. Brendan Gan 70?
Red Cards: 14. Nick Stavroulakis 76?
Sydney United: 30. Vedran Janjetovic, 3. Joe Moric (9. Chris Soares 78?), 5. Damon Collina, 6. Joe Vrkic, 15. Chris Boyle, 18. Andrija Petkovic (19. Mitchell Thompson 61?), 23. Ivo Bosnar, 14. Peter Markovic (16. Elsid Barkhousir 63?), 21. Saso Petrovski, 13. Ben Vidaic, 11. Luka Glavas
Substitutes not used: 4. Milan Bosnar, 20. Steve Minovski
Yellow Cards: 5. Damon Collina 35?, 3. Joe Moric 50?
3 ? Jim Bakis (SS)
2 ? David Huxley (SS)
1 ? Michael Katz (SS)
-By Micky Brock