SAINTS take on Wigan tonight in arguably the most important derby clash between the sides since the 2014 Grand Final.

The teams are level on 27, with Saints fifth by virtue of a better points difference, but both are eyeing Wakefield in fourth.

The team that wins tonight keeps the destiny of that semi-final qualification in their own hands with time running out.

The loser is not necessarily out, but with three games then to go they would become reliant on teams above them slipping up.

The match is vital.

In games between the sides it is one game apiece so far this season, with Saints losing on Good Friday after having Kyle Amor harshly sent off for a high tackle.

They avenged that in May, in Justin Holbrook's second game in charge, when Mark Percival leapt to Matty Smith's kick to snatch the spoils.

There are plenty to add to this mix than the usual derby feeling.

Wigan come into keen to bounce back after their Wembley defeat - and no doubt feeling hard done to.

They will not want to see the door to silverware slam shut for the second time in a week.

The spirit will be willing - but how much will have the physicality and emotion of Wembley taken out of them?

But Saints, too, will be desperate to keep their year alive - not least because they have strengthened ahead of the business end.

After losing the last two games by narrow margins, a third consecutive loss would prick the bubble that has been inflating since May once and for all.

Saints hand a debut to Ben Barba - and although great things are expected of him, having not played for 10-months he will get better as the month progresses.

But they have to win tonight to see that happen.

Barba slots in at one – his natural position in the NRL - and Holbrook hopes that will give them that extra cutting edge in the keenly-fought games.

It has meant a reshuffling of the side, with Jonny Lomax displacing Theo Fages at stand off.

He will partner Matty Smith in the halves.

It is a big re-shuffle - and a gamble - but one that Holbrook needed to take to slot in a genuine superstar.

Barba will have plenty of attention - and he will get plenty of tough tackling and aerial bombardment to test him in his first game back in the 13-man code.

Saints skipper Jon Wilkin said: “Wigan will scrap. The Challenge Cup final showed what they are all about because they are a dogged team and they kept in there.

“There is no doubt in my mind every one of their players will turn up ready to play on Friday.

“This is a huge game – both teams play-off ambitions ride on this game.

“Although it is not the end if we lose, it certainly becomes difficult to make the four.”

“It has plenty of things in the mix; it is just after the cup final, it is a derby, it is massively important in the context of the season and we have Ben Barba coming into the team.

"Our defence has been outstanding. The challenge for us this week is unlocking Wigan because they are a great defensive side too, we need to get our attack and defence on the pitch of the same time.

"Our defence has been a stand out feature – but bringing Ben Barba in a team with Jonny Lomax, Matty Smith, James Roby and Mark Percival makes us a threat."

The game has not sold out and cash turnstiles are available tonight.