|Betfred Super League|
|St Helens (4) 4|
|Castleford Tigers 0 (0)|
Beaten Challenge Cup finalists St Helens battled back from last weekend's Wembley defeat to earn their hardest-fought Super League win of the season and dent Castleford's top-five hopes.
Welsh winger Regan Grace went over in the left corner for the only score of the game in the 33rd minute.
Saints then somehow kept out the fired-up Tigers' second-half onslaught.
Victory for Cas would have lifted them up into fifth following Hull's shock home defeat by Huddersfield.
As it is, they stay sixth and now host fifth-placed Hull next weekend at Wheldon Road in a contest which may well sort out who gets the final top-five spot - and a place in the play-offs.
Grace's try, fashioned by James Roby and Mark Perciva, maintained his record of scoring in all Saints' meetings with Cas this season. And that at least ensured some happy home faces on the night when Saints picked up the League Leaders' Shield.
Saints are now 18 points clear at the top, having won 24 of their 27 games this season as they kept up their 100% home record.
Cas, who have not won at St Helens since 1992 - and never since their hosts left Knowsley Road for Langtree Park in 2012 - had a succession of second-half openings.
But Saints' defence, so surprisingly breached by Warrington at Wembley six days earlier, this time held firm.
And, after Danny Richardson's missed conversion of Grace's try, the closest either side came to another score was when Saints' Jonny Lomax had a late try unfairly chalked off for obstruction.
But referee James Child's decision ensured that Saints equalled their own record for Super League's lowest-scoring game, a 4-0 away win over Celtic Crusaders in March 2009, at the Brewery Field, Bridgend.
St Helens coach Justin Holbrook:
"It was obviously a hard week for us and to put in a display like that and show such character was terrific.
"We worked really hard with some tired bodies out there. It was hard to get the players up for the game after the disappointment of not winning the Challenge Cup but the Super League is our main focus.
"The players kept turning up and we needed that. The fans knew how tough it was for us and the way we hung on there was terrific.
"To be the most consistent side after 29 rounds is a huge accomplishment. To play consistently is very hard to do."
Castleford assistant coach Ryan Sheridan:
"I am proud of our players. They gave it their best. But you've got to take your opportunities and our kicking game was a bit off.
"It was a very tough game and a lot went into it from us. We can take a hell of a lot from that performance.
"We created quite a few opportunities but Saints defended really well and were so hard to break down.
"For us to come away from a champion team like Saints with only a four-point loss is an achievement but disappointing."
St Helens: Welsby; Makinson, Costello, Percival, Grace; Lomax, Richardson; Amor, Roby, Thompson, Ashworth, Z Taia, Knowles.
Interchanges: Walmsley, Paulo, McCarthy-Scarsbrook, Bentley.
Castleford: Rankin; Clare, Mata'utia, Blair, Minikin; Trueman, Ellis; Watts, McShane, Millington, Holmes, McMeeken, Massey.
Interchanges: Milner, Sene-Lefao, O'Neill, Smith.
Referee: James Child.
Sat 31 Aug: Catalans v Hull KR
Sun 1 Sept: London Broncos v Leeds, Wakefield v Wigan
Fri 6 Sept: Leeds v Salford, St Helens v Huddersfield, Warrington v Wakefield, Wigan v Catalans
Sun 8 Sept: Hull KR v London Broncos, Castleford v Hull
Fri 13 Sept: Huddersfield v Catalans, Leeds v Warrington, Hull v St Helens, Wigan v Castleford
Sun 15 Sept: Wakefield v London Broncos, Salford v Hull KR