St Helens remain firmly on course for a fourth successive Carnegie Challenge Cup triumph after seeing off Super League champions Leeds in impressive fashion at Headingley.

Saints may have lost the last two Grand Finals to their arch-rivals but they are unbeaten in the cup since a semi-final defeat by Hull in 2005 and the competition once more brought the best out in them.

England forward Jon Wilkin was the hero for the holders with a superb display, which included two crucial 40-20 kicks, despite playing out of position at stand-off.

The Rhinos briefly held the lead, courtesy of Jamie Jones-Buchanan's 24th-minute try, but they were a clear second best for the second time in a fortnight and defeat leaves them still looking for their first Challenge Cup success since 1999.

Leeds left out Ryan Bailey, the man who caused so much furore for his part in the recent feisty league match at Knowsley Road, but tempers still ran high and referee Phil Bentham had to speak to the captains in an attempt to calm things down.

It did the trick as both sides concentrated on producing a rugby feast for the 17,689 sun-kissed spectators.

St Helens demonstrated their confidence early on by twice ignoring the chance to kick at goal after being awarded penalties and the pressure paid off on 14 minutes when skilful handling by centre Matt Gidley enabled winger Ade Gardner to score the game's opening try.

Part-time marksman Paul Wellens was off-target with the conversion attempt and Leeds went in front when skipper Kevin Sinfield produced a clever kick for second-rower Jones-Buchanan to touch down, with Sinfield adding the goal.

There was typically little to choose between the two Grand Finalists but Saints regained the initiative with the introduction of substitute hooker James Roby midway through the first half.

Gardner had a second try disallowed because of a forward pass but regained the lead on 30 minutes when Roby caught the Leeds defence napping and darted through for a solo try straight from dummy-half.

Wellens this time added the goal and the visitors were pressing again, courtesy of Wilkin's first 40-20 kick, when the half-time hooter brought relief to the Rhinos.

It was only a temporary respite, however, with Wellens stretching Saints' lead with a penalty seven minutes into the second half after Leeds prop Kylie Leuluai was caught ball-stealing.

The Rhinos ought to have made more of a clean break by scrum-half Rob Burrow and they were given a lesson in finishing as Saints struck twice in seven minutes to pull away.

Another 40-20 kick from Wilkin gave the holders a perfect attacking position and they made it count with Roby and Leon Pryce working the ball out from the scrum for Wellens to touch down.

Man-of-the-match Wilkin then sent Gidley racing over at the corner to make it 20-6 but full-back Brent Webb gave Leeds hope on the hour when he took a return pass from centre Keith Senior to score his side's second try.

Sinfield's goal made it 20-12 but Wellens eased any fears they might have had with a second penalty on 64 minutes.

In a late flourish, Ablett sent Senior over for the home side's third try and Sinfield's conversion went in off an upright to cut the deficit to just four points but there was no time for Leeds to press for the winner.