Highlights from a crucial set of fixtures in the Super League and the qualifiers, as play-off places and potential promotion are on the line with just three weeks to go.Leeds Rhinos return to the scene of their biggest defeat of the season when they go to Castleford Tigers. The Rhinos were hammered 66-10 there in March, one of three defeats they have suffered at the hands of Castleford this season.There's a repeat of the Challenge Cup final as Hull FC take on Wigan, Wakefield are at home to St Helens and Salford have a home game against Huddersfield.Hull Kingston Rovers look to continue their quest for promotion when they take on Widnes. Rovers won their first three games in the qualifiers to put themselves within touching distance of a return to Super League for 2018. Catalans hope to ease their relegation fears when they take on Featherstone, Warrington are at home to Leigh and London Broncos play Halifax.