The Warrington Wolves have opened up a five-point gap on St Helens following a 22-12 victory at Langtree Park on Monday night.
Saints knew a win over their rivals could open up the race for second place, although it was Tony Smith's side who secured the spoils.
Early tries from Brett Hodgson and Chris Hill put the visitors in control before Michael Shenton pulled one back for the home side.
Second-half efforts from Trent Waterhouse and Chris Riley wrapped up the two points, although Paul Wellens had the final say with a 75th minute score.
Saints went into the game on the back of an unbeaten seven-match run going back to May but they were always second best against opponents running into form at the right time.
Double-chasing Warrington, who have now won their last five games, lived up to their reputation as quick starters as they made the most of Tommy Makinson's enforced goal-line drop-out inside the first minute.
Half-backs Richie Myler and Lee Briers worked the ball out wide for Hodgson to scythe through for the opening try and it was 10-0 on seven minutes after prop Chris Hill picked up a loose ball to touch down.
Saints simply had no answer to the pinpoint kicking of Briers and, had Joel Monaghan's15th minute try been allowed to stand, they would surely have been out of sight by then.
But video referee Phil Bentham ruled the Australian winger had lost control of the ball in claiming Briers' high kick and the home side made the most of the let-off to claw their way back into the game, aided by a string of penalties.
They missed a glorious opportunity when Francis Meli broke down the left wing only to see Jonny Lomax spill the final pass - but centre Michael Shenton got over the line midway through the first half when he took Wellens' pass to twist and turn his way through a series of attempted tackles and touch down.
Makinson's conversion cut the gap to 10-6, which is how it remained up to half-time, but the Wolves restored their 10-point advantage within three minutes of the restart and went on to dominate the second half.
Second rower Trent Waterhouse timed his burst to perfection to run onto Hodgson's short pass and score his side's third try, with Hodgson kicking his second goal.
The visitors were denied another try when slow-motion replays indicated winger Chris Riley had put a foot in touch but it only delayed the inevitable.
A desperate tackle by St Helens stand-off Lance Hohaia denied Myler a long-range try and Riley had another effort disallowed for a forward pass but he finally got his reward when he picked up a looping pass from Ryan Atkins to go over on 62 minutes.
Hodgson kicked his third goal but St Helens gained some consolation when Wellens supported a break by substitute Mark Flanagan to score his side's second try six minutes from the end.
Makinson kicked his second goal but Warrington were still attacking at the end and Briers was the latest player to have a try disallowed.