Sinfield’s goalkicking was the difference as Leeds booked their fifth trip to Old Trafford in six years with a gripping 13-12 win over Wigan on Friday.
It means that in two seasons in charge, former Harlequins coach McDermott has led the Rhinos to five finals out of a possible five – including this year’s World Club Challenge win.
Sinfield told the club’s official website: “I have to say that Brian McDermott is the best coach I have ever played under. His combination of tactical awareness, player development and man management is second to none and I am so pleased for him that we have got back to yet another Final. The backroom team of James Lowes and Jason Davidson perfectly complement Brian and together they give us everything we could possibly need to succeed.
“Sometimes things don’t go our way in the season but we stay tight and continue to work hard for one another. That happens in life and how you handle that adversity makes you what you are.”
Sinfield’s four goals and a drop goal helped to set up a Grand Final clash against Warrington, where the Rhinos will be hoping to gain revenge for their Challenge Cup final defeat in August.