St Helens underlined their status as engage Super League title favourites with a hard-fought victory over Leeds to maintain their 100 per cent start to the season.

Leeds' teenager Danny Williams enjoyed a fairytale debut by scoring the first try of the match but it was not enough to prevent the Rhinos' first defeat.

Saints trailed until second row Lee Gilmour struck in first-half stoppage time while winger Francis Meli scored the only try of the second half.

Leeds, 19-16 winners on their last visit to Knowsley Road in October, had the encouragement of an early break by second row Jamie Jones-Buchanan, a late replacement for Great Britain international Gareth Ellis.

And they thought they had scored on eight minutes when 19-year-old Williams collected a kick from Kevin Sinfield only for video referee Steve Presley to rule he was in front of the kicker.

Both defences were on top but Saints had difficulty coping with Leeds' clever kicking game.

Stand-off Danny McGuire, pinpointed by St Helens coach Daniel Anderson as a major threat, knocked on in a great position after Ali Lauitiiti had intercepted a Saints pass.

Some delightful passing from Saints' internationals Leon Pryce and Jamie Lyon promised much and the home side had a try disallowed on 17 minutes when winger Ade Gardner was denied by a forward pass.

The breakthrough came on 23 minutes when Williams showed great pace to reach full-back Richie Mathers' grubber kick to the line and this time referee Ashley Klein had no reason to refer the decision.

Sinfield missed the difficult conversion and the Rhinos went behind just before half time when Gilmour took a short pass from prop Paul Anderson to crash through for a crucial try.

Lyon added the simple goal to edge his side 6-4 ahead by the break.

It was just as tense in the second half as both sides sought to gain the upper hand, although handling errors ruined many a promising move.

Both teams had ignored chances to kick penalty goals in the first half but the temptation proved too great for Saints on 50 minutes after Shane Millard was pulled up for interference at the play-the-ball.

Captain Paul Sculthorpe asked Lyon to go for the two points and the Australian duly obliged, edging his side into an 8-4 lead.

That was just the encouragement St Helens needed as they began to pile on the pressure, which paid off almost immediately.

Man of the match Pryce sent out a long pass to the wing where Meli stepped inside Rob Burrow to touch down and extend his side's lead.

That was the signal for Sculthorpe to take a breather but vice-captain Sean Long strengthened his side's hold on the game by adding a drop goal to complete the scoring.