THE state's most marginal seat was too close to call last night with both candidates unwilling to claim victory.
Incumbent Liberal Matt Williams and Labor repeat candidate Steve Georganas were regularly neck and neck during counting yesterday. 
At the end of the night Mr Georganas had just edged ahead on the two-party preferred vote.
Both men said the outcome was "too close to call" and expected it could take days to reach a final result.
There are about 19,000 prepoll and postal votes still to count. Liberal Senator Simon Birmingham said Labor "has got its nose in front" but his party "should be optimistic" about holding the seat.
"Hindmarsh is classically a seat that comes down to terribly narrow margins," he said.
Mr Birmingham ran unsuccessfully in Hindmarsh in 2004, but lost to Mr Georganas by 108 votes.
Mr Williams took Hindmarsh from Mr Georganas in 2013, on a 1.9 per cent margin. "There's a long way to go, ... indications are that we're getting closer," Mr Williams said last night. "Based on history ... when it gets down to a few hundred votes it does take some time." An Advertiser-Galaxy poll conducted less than two weeks before the election showed a 50-50 split between the major parties in the western suburbs seat.
Mr Williams said he expected the presence of NXT's Daniel Kirk would make the result harder to predict. "We're just uncertain where those preferences will go," he said.
Both major party candidates placed Mr Kirk fourth on how-to-vote cards. All three men were expecting a long wait for the result as they greeted voters at booths from early morning.
"I've worked as hard as I can to get some great results using my influence in Canberra," Mr Williams said.
Mr Georganas said he had secured a "wafer-thin margin" in 2004 and he felt this year "will be no different".
"We've done everything possible in the last few weeks to get our message out there," he said.
HINDMARSH WILLIAMS (LIB) GEORGANAS (ALP) KIRK (NXT)IN DOUBT