It is the morning after the Edinburgh derby when a late goal on a grim, sodden evening gave Heart of Midlothian three points, widening their gap at the top of the Scottish Premiership.

Head coach Derek McInnes didn't get to sleep until 2am, but if the 54-year-old is fatigued, he has disguised it well as he strides into the home dressing room for our interview.

"I tossed and turned with the adrenaline. It was a late night, but it's always better when you win!" he says, smiling.

McInnes and his side certainly have stamina. Hearts have led the Scottish Premiership since October and the whisper they could win the league has risen to a roar.

Can he believe their success so far?

"No," McInnes answers honestly. "I wouldn't have thought we could be where we are, but it just shows you what can be done."

It's rare for a team outside the Old Firm to be top of the league in February.

In fact, the last time a club stopped the dominance of Rangers and Celtic in the top tier of Scottish football, it was the 1980s and a young Sir Alex Ferguson was steering Aberdeen to three titles, four Scottish Cups and the 1983 European Cup Winners' Cup.

Iconic former Manchester United boss Ferguson is a figure McInnes admires greatly.

"I'm fortunate enough that I speak to Sir Alex regularly," he says. "He was on the phone on my way into the game and he's got great pointers, little nuggets of information.

"He's able to give you wee things you can maybe do and say, like how you deal with the press."

I wince, remembering how Ferguson was known for banning members of the media for asking awkward questions, but McInnes is charm personified.

He says Ferguson plans to come to Tynecastle in the next few weeks for a match and he's looking forward to taking advantage of the 84-year-old's experience and depth of knowledge.

"He knows all my players. He talks as though he knows them intimately and I tell my players that, and they still can't believe that he actually knows our game inside out," adds McInnes.

"He watches forensically. So I feel as if I've got a real supporter there."

Another 'supporter' that's made all the difference to the club is shareholder Tony Bloom.

In June last year the majority owner and chairman of Brighton bought a 29% stake in Hearts, announcing he planned to "disrupt the pattern of domination which has been in place for far too long" in Scottish football.

The implication was a 10-year plan - no-one foresaw success like this so quickly.

However, McInnes says it's a holistic approach that's helped the club get to this position.

"We're not suddenly awash with money," he adds. "We're not paying huge transfer fees for every player that comes in the door. We're being smart on the recruitment side of it."

He was happy to see Bloom watching on Tuesday, though, because "every time he's come we've won".

And what about the fans? This is a new feeling for many of them.

The last time Hearts came close to winning the league was on a dramatic final day of the 1985-86 season.

A 2-0 defeat by Dundee, coupled with Celtic's 5-0 win over St Mirren meant the Hoops were champions on goal difference by a margin of three.

Olympic bronze medallist and lifelong Hearts fan Eilidh Doyle was born the following year, so this is now uncharted territory for the 38-year-old.

"It's probably not something I thought I'd see in my lifetime, so it's a really strange feeling," says Doyle.

The retired 400 metre hurdler has a season ticket at Tynecastle.

"It's a very Scottish thing to not want to jinx it, but it's the first time that realistically you think 'we could go and do this'."

In the stands, the club's support has swollen and grown a life of its own.

A song about Portuguese striker Claudio Braga went viral on social media a few months ago.

It was written by fan, Calum MacKenzie, inspired by a success he's never known before.

"It's a tune, eh?" says the 26-year-old with a smile as he looks around Tynecastle. "It feels like the players are feeding off the stands and the energy."

His song has been part of that.

To the tune of Queen's Radio Gaga, Mackenzie wrote it at work, recorded it on a voice note and sent it to a Hearts supporters' Whatsapp group.

Someone put it on social media and it made its way to the stands where mobile phone footage of fans belting it out has been watched more than five million times.

"Luckily enough we're doing well and Claudio is a good player so it gets sung a lot more than I expected," adds Mackenzie. "If we win the league now I'll be taking the credit for it!"

Hearts fans are allowing themselves to think in those terms, albeit warily. However, McInnes will not be drawn on the possibility of lifting that trophy, but he is appreciative that they're 'disrupting' Scottish football.

"We were a good story at the start - like good old Hearts are up there competing, and nobody really thought we could go this far," he says.

"I think we're starting to annoy a few people, which is understandable when there has been such a strong presence over the last 40 odd years for Rangers and Celtic."

His side have two wins and a draw against Celtic in the league and two victories over Rangers, who they face at Ibrox this weekend.

Their record against the Old Firm is strong this season, but McInnes feels he can't take his eye off the task in hand for one moment.

He adds: "I have to enjoy it more. If I was outside looking in and seeing a manager at the top of the league for nearly five months, I'd think how good must his life be!"