St Helens ran in five second-half tries as they beat Hull FC to maintain their unbeaten start to Super League.
Mickey Paea and Richard Whiting tries gave Hull a 10-6 half-time lead.
But scores from Sia Soliola, Jonny Lomax and James Roby, who also scored a first-half try for Saints, put the hosts in command.
Gareth Ellis crossed as Hull hit back, but Tommy Makinson and Mark Percival touched down to make the game safe before Danny Houghton's consolation.
Saints sit top of the table, level on points with Leeds, who beat Warrington 18-12 on Friday.
Emotional tributes were made to the late Steve Prescott before kick-off. The former England and Ireland full-back played for both St Helens and Hull FC and died last year after battling cancer for seven years.
The match was the first of a new cup set up in Prescott's name, with the aggregate winner from the two league games between the sides to be awarded the trophy annually.
Hull broke the deadlock after three minutes when Paea crossed, but it was quickly cancelled out by Roby, who danced his way past full-back Jamie Shaul to score.
After setting up the opener, Joe Westerman was again instrumental in Hull's second as he produced a brilliant offload to send Whiting over for a try converted by Ben Crooks.
The hosts lost centre Jordan Turner, who was concussed before the interval, and Hull also suffered an injury blow as prop Garreth Carvell damaged ankle ligaments. He will have a scan on Monday.
Despite Turner's absence, Saints went ahead when Soliola powered over from close range.
Lomax increased St Helens' advantage, crossing over in the corner, and Soliola set up Roby for his second under the posts.
Hull responded as Aaron Heremaia put Ellis over, but Makinson touched down wide on the right to maintain Saints' hold on the game.
Saints broke through some weary tackles to set up a sixth try, for Percival, with just under four minutes remaining, and scrum-half Luke Walsh landed his fifth conversion.
Houghton slid over for Hull in the last minute and Crooks kicked a third goal.
St Helens coach Nathan Brown:
"To end up getting the result was pleasing but the first half was not where it needs to be.
"Our attitude was not very good. The way it looked to me was we thought we were going to go out there after a good win last week and things were going to happen.
"But if you don't do the hard, tough things early, you have a chance of coming unstuck.
"I think the players understood what they did in the first half was not acceptable.
"They are a great bunch of guys, all hard workers. They knew what they tossed up wasn't good enough."
Hull FC coach Lee Radford:
"We had some real smart game management and if we had continued to do that for long periods we would have been fine.
"But for whatever reason in the second half we went away from that.
"It was just poor game management from our supposedly smart players. We went into our shells a bit and came up with some really dumb errors coming out of our own end.
"We backed that up with some ill discipline and before we knew it we were camped on our own tryline for long periods. Against a quality side you can't do that."
St Helens: Lomax, Makinson, Turner, Percival, Swift, Wheeler, Walsh, Amor, Roby, Walmsley, Wilkin, Manu, McCarthy-Scarsbrook.
Replacements: Wellens for Turner (35), Soliola for Amor (24), Jones for Walmsley (12), Laffranchi for McCarthy-Scarsbrook (23).
Hull: Shaul, Lineham, Crooks, Arundel, Talanoa, Rankin, Horne, Paea, Houghton, Carvell, Ellis, Whiting, Westerman, Bowden.
Replacements: Bowden for Paea (22), Heremaia for Houghton (30), Paleaaesina for Carvell (19), Thompson for Bowden (49).
Ref: Richard Silverwood (RFL).