The veteran stand-off was restored to the Rhinos’ starting line-up in the absence of Liam Sutcliffe, ruled out for the season with a ruptured anterior cruciate ligament, and he rolled back the years with a dominant display in a 24-6 victory over Hull in the second quarter-final.
Sinfield kicked three long-range penalties – and was close to landing two others – as well as converting tries by centres Joel Moon and Kallum Watkins and full-back Zak Hardaker as the Rhinos mastered the wet conditions at a rain-soaked KC Stadium.
Sutcliffe was forced to watch his mentor fill his boots from the stands after being hurt in last Sunday’s 32-20 Super League win over Hull, a match that also produced injuries that forced prop Adam Cuthbertson and Danny McGuire to relinquish their ever-present records.
However, Leeds coach Brian McDermott was able to turn to the tried and trusted Rob Burrow alongside Sinfield at half-back and he played his part in an impressive all-round team performance.
The only try of the first half came on five minutes, before the heavy drizzle began to descend on the KC Stadium and turn ball-handling into a lottery.
Moon outjumped Hull full-back Jordan Rankin to regather the ball from his own kick and touch down.
Sinfield added the conversion and succeeded with two out of three long-range penalty attempts to extend his side’s lead to 10-0 at half-time.
The decision of the Rhinos skipper to take any points on offer demonstrated the difficult conditions, with tryscoring opportunities always likely to be at a premium.
Sinfield’s only miss actually set up one of Hull’s most dangerous attacks, with Rankin sprinting 60 metres upfield only for the move to quickly peter out in all too familiar fashion for the error-strewn home side.
Leeds continued to play to the conditions, with Sinfield content to pin the home side back with his shrewd tactical kicking, and the visitors – who join Hull KR in tomorrow’s semi-final draw – struck a decisive blow two minutes into the second half.
Left winger Ryan Hall sensibly switched the direction of play after finding his path to the line blocked and Sinfield’s sublime inside pass opened up the Hull defence for Watkins to stride through for the Rhinos’ second try.
Sinfield made it 16-0 with the conversion and hit the crossbar with an ambitious penalty from a metre inside the Hull half.
Hull’s last chance to get back in the contest disappeared when loose forward Joe Westerman lost grip of the ball in a promising position 20 metres out from the Leeds line.
He repeated the sin midway through the second half while skipper Gareth Ellis also came up with a knock-on following a rare sustained spell of pressure.
Leeds clinched the win against the run of play when Hardaker finished off a glorious move involving Sinfield to score a third try 10 minutes from the end.
The skipper added the goal and kicked another penalty from near halfway before Hull scrum-half Jordan Abdull, deputising admirably for the suspended Marc Sneyd, grabbed a consolation try five minutes from the end.
Sutcliffe will undergo knee surgery next Thursday.
Rhinos’ head coach Brian McDermott said: “It is desperately disappointing news for Liam especially given the form he has been in this season.
“He will get the best possible treatment from our medical team and I am sure he will return next season stronger for the experience.”
Hull: Rankin, Lineham, Michaels, Yeaman, Talanoa, Pryce, Abdull, Paea, Houghton, Watts, Ellis, Minichiello, Westerman. Substitutes: Paleaaesina, Bowden, Thompson, Whiting.
Leeds: Hardaker, Handley, Watkins, Moon, Hall, Sinfield, Burrow, Leuluai, Aiton, Peacock, S. Ward, Keinhorst, Ablett. Substitutes: Singleton, R. Ward, Yates, Delaney.