Lee Smith rounded off his Leeds Rhinos career with a two-try contribution towards a third Grand Final winner’s ring, although the centre’s switch of codes with London Wasps will almost certainly be delayed by a call-up today to England’s Gillette Four Nations squad.

“I played union when younger and I back myself,” Smith, 23, said. “I’ll work hard, because I need to get the respect of Wasps before I do anything. Hopefully, some will have been watching the final and that will have given them a good impression.

“Shaun Edwards [the Wasps coach] has been brilliant [allowing Smith to stay on for the Four Nations], because he knows it’s an honour to play for your country. If I’m picked, it will be a great way to go out after this.”

Smith’s 73rd-minute try was decisive in putting Leeds two points clear. However, St Helens remain unconvinced by the decision of Phil Bentham, the video referee, based on the view of a rail camera running across the South Stand at Old Trafford, that Smith was onside when Danny McGuire angled a kick for him to burst on to. “I thought I was just level to be honest,” Smith said. “You get some and not others, but it was a great kick from Danny.”

Although disappointed with the decision, Mick Potter, the St Helens coach, said: “I try not to look at the screen. I just asked the bench how it was looking and they thought it was offside. I thought it was going to be ‘no try’ and was focused on what we were going to do next. I will probably look at it some stage but that is the way it goes.”

In a ferocious encounter of unyielding defence and no quarter given, St Helens were eventually ground down by Leeds’s sheer force of will.

Too much was asked of James Graham and Tony Puletua up front against an unrelenting Rhinos pack, while Brent Webb was rock solid at the back of the Leeds defence under Sean Long’s siege-gun boot. The pity was that Kyle Eastmond did not see more ball after his blistering finish and two goals gave St Helens an early 8-0 platform.

Matt Diskin drove over and Smith profited from Francis Meli’s failure to clear McGuire’s dangerous grubber for a second Leeds try in the space of seven minutes before the break, after which Sinfield nudged Leeds ahead with a dropped goal.

Apart from a second penalty by Eastmond, there was no way through for St Helens in the second half. Keiron Cunningham, struggling with a broken bone in his hand, conceded the penalty that enabled Sinfield to make it 11-10, before Smith’s contentious but decisive intervention.

Scorers: Leeds Rhinos: Tries: Diskin, Smith 2. Goals: Sinfield 2. Dropped goals: Sinfield, Burrow. St Helens: Try: Eastmond. Goals: Eastmond 3.

Leeds Rhinos: B Webb; S Donald, L Smith, K Senior, R Hall; D McGuire, R Burrow; K Leuluai, M Diskin, J Peacock, J Jones-Buchanan, C Ablett, K Sinfield. Interchange: A Lauitiiti, R Bailey, I Kirke, L Burgess.

St Helens: P Wellens; A Gardner, M Gidley, K Eastmond, F Meli; L Pryce, S Long; J Graham, K Cunningham, T Puletua, C Flannery, J Wilkin, L Gilmour. Interchange: B Hargreaves, M Fa’asavalu, J Roby, P Clough.

Referee: S Ganson.