BEFORE a single vote is even cast, three seats in Cork South-Central are already filled.

Simultaneously one of the most notable constituencies and one of the least interesting, the southside is dominated by three of the biggest figures in Irish politics.

One is Micheál Martin, the leader of Fianna Fáil and potentially the next Taoiseach.

There’s Simon Coveney, Tánaiste and a key figure in Fine Gael’s re-election campaign.

Then there’s Michael McGrath, the Fianna Fáil finance spokesperson who is able to outpoll even his own party leader.

With those three all certain to hold their seats — the fourth election in a row that the three will be heading to Dáil Eireann together — the fight over the fourth seat is where the real action will be seen.

This time that will be a triple threat match between incumbent Sinn Féin TD Donnchadh Ó Laoghaire, former Fine Gael TD and current Seanad leader Jerry Buttimer, and upstart Green Party councillor Lorna Bogue.

Looking into the weekend, this could be a real nail-biter, as there are so many competing forces at play.

Mr Ó Laoghaire has an obvious advantage as an incumbent, but he will also be buoyed up by a surge for his party in recent weeks as Mary Lou McDonald leads a barnstormer of a national campaign.

But Ms Bogue is riding a different kind of green wave, with a national surge for her party in the last 12 months — a surge that saw the party elect three councillors across the constituency with about 5,000 votes across the Cork South-Central boxes.

However, Mr Buttimer cannot be ruled out entirely. Though Fine Gael has stagnated a little, Mr Coveney’s star rising, combined with the Senator’s constant canvassing over the last four years, could see this constituency buck the national trend.

It would take a tremendous vote sharing strategy, however, as the party would need to ensure that the Tánaiste doesn’t absorb the Fine Gael vote.

Though Mr Ó Laoghaire is favourite to take this, transfers will mean everything.

He was a transfer magnet back in 2016, with almost every left-wing vote finding its way back to him.

The most likely situation is that this constituency will return the same team as 2016, but don’t be surprised if there’s an upset.