The race for Angus was expected to go down to the wire despite the Tories seeking to overturn an SNP majority of 11,230.
The count got under way at the Saltire Centre in Arbroath amidst an increased security presence in the wake of the recent UK terror attacks.
An exit poll by politics professor John Curtice had earlier given the Tories a 90% chance of taking Angus from the SNP.
However, those on the count floor weren’t getting carried away although North East Scotland Conservative MSP Liam Kerr said it will be “no surprise” if Kirstene Hair took the Angus seat from Mr Weir, who has held it for 16 years.
Last month’s local government result saw four Tory councillors grab seats from the SNP for a total of eight – and the most first preference votes in seven of eight wards.
“All I care about is that Angus has a really good hard working MP who will stand up for the people and businesses here in the heart of government,” said Mr Kerr.
“It is clear that that is Kirstene Hair and people can see that.
“They also see that Mike Weir simply hasn’t delivered for them and has been all but anonymous.
“They want change and it will be no surprise if they ask Kirstene to be that change.”
Ms Hair previously stood for election as MSP for Angus South in 2015, losing out to SNP incumbent Graeme Dey.
That battle saw Mr Dey’s majority cut from 38.3% to 13.4% — 15,622 votes to 11,318 for the Tory.
The duo are up against local opposition from William Campbell of Labour, and Lib Dem Clive Sneddon – both huge outsiders – who are hoping to turn their campaigns into gains at the expense of either party.
North Angus and Mearns SNP MSP Mairi Evans said they were “very proud” of Mr Weir’s campaign which has taken the message to “every corner of the constituency”.
She said: “We’ve fought a strong and positive campaign.
“We have focused on the needs of the people of Angus, while the Tories have hidden behind their opposition to constitutional change to mask some of the appalling policies they want to implement if elected.
“Mike Weir has also campaigned strongly against a hard Brexit and the devastating impact it could have on the local economy.
“We have never taken any single vote for granted and have always fought the hardest we can – this election has been no different.
“We’re very proud of the campaign throughout Angus and our activists have been outstanding in taking our message to every corner of the constituency.”