Saints came from behind, as Daryl Clark's try and Tyrone Roberts' goals put the Wire 8-0 in front at half-time.

Ben Barba and Jonny Lomax tries brought the home side level after the break, setting up the thrilling finale.

Both sides missed drop-goal attempts late on, before a penalty on the hooter gave Saints the chance to snatch it.

They now lead Super League by 12 points from second-placed Wigan, who host Catalans Dragons on Friday.

Saints face Catalans in the first Challenge Cup semi-final at Bolton on Sunday, 5 August looking to reach their first final since 2008, while Warrington go up against Leeds later the same day.

Richardson has been a stand-out player in the Saints' surge towards Super League success, contributing five tries and 101 goals - although few could be as impressive as the one from 55 metres he nailed at the end of a bruising, enthralling encounter.

The moment evoked memories of the match-winning brilliance of former Red Vee halfback Sean Long, who, as part of Justin Holbrook's coaching staff, looked on as St Helens showed championship mettle to come away with the points.

Warrington's first-half game plan was executed to perfection as they stemmed the Saints flow and limited space, and Clark's dart across from a bludgeoning Mike Cooper run and offload was their reward in attack.

However, once Saints scored within a minute of the second-half restart through Barba after Mark Percival's break the tide turned, they grew in confidence and drew level when Zeb Taia's inside ball released Lomax to level.

Roberts, who kicked four from the tee, was unable to find the target with two drop-goal attempts as Steve Price's Warrington pressed for the points, and nor could Richardson convert in reply.

Yet once the penalty was awarded, the 21-year-old showed composure and poise to slot the goal and give the Super League leaders a lift as their chase for the treble continues next week.

St Helens coach Justin Holbrook:

"[Sean] Longy has a lot of confidence in him because Tom Makinson kicks the ball a long way and I said 'we should give it to Tom to kick it'.

"But Longy said 'no Danny will kick this' and he did. It was outstanding for a young kid to have the confidence to step up at the end of the game and kick it.

"He's everything you want in a young player, you want them to back themselves and he gets it done."

Warrington coach Steve Price:

"I'm really proud of the guys. I thought the effort was outstanding. We had three or four field goal attempts to win the game but we couldn't finish it off.

"I thought it was a good old tough game of football, with two quality teams going hard at it, and in the end there was not much between them.

"It was end to end and I'm sure the spectators enjoyed it.

"Full credit to St Helens, that's why they are where they are, they're a quality football team. We will take a lot of confidence out of that. We'll dust ourselves off, we've a really important game against Leeds next week."

St Helens: Barba; Makinson, Morgan, Percival, Grace; Lomax, Richardson; Amor, Roby, Thompson, Peyroux, Taia, Wilkin.

Replacements: Fages, McCarthy-Scarsbrook, Douglas, Knowles.

Warrington: Ratchford; Lineham, Goodwin, T. King, Charnley; K. Brown, Roberts; Hill, Clark, Cooper, Livett, Hughes, Westwood.

Replacements: Murdoch-Masila, Patton, Akauola, Philbin.

Referee: James Child (RFL)