Senior is thought to have damaged ligaments in his right ankle when he was tackled by Joe Vagana during the defeat by Bradford on Friday night and was having a scan yesterday.
"When I first heard the crack, especially with big Joe on top of me, I feared the worst," Senior said. "Fortunately, it doesn't seem to be as bad as I first thought. It wasn't until I got in the changing-room did it hit me that there's a big game this week."
The Rhinos coach, Tony Smith, says that he will give Senior as long as possible to show that he will be fit to face Hull at Cardiff's Millennium Stadium.
"If he can give me until Friday - great," Senior said. "I'm hopeful, but I'm not getting my hopes up too high."
Senior remains the major doubt for Leeds, who are confident that Danny McGuire and Mark Calderwood will both be fit for the final. Willie Poching is due to have an X-ray today on the cheekbone he fractured and his chances of playing will hinge on that.
Hull have a clean bill of health, with their winger Gareth Raynor recovering from a knock to the leg after Sunday's 24-28 defeat by Wigan.
The Widnes forward John Stankevitch has announced his retirement at the age of 25, because of a persistent shoulder injury.
Stankevitch has played 22 times for Widnes this season after joining them from St Helens, but is retiring on medical advice.
Doncaster will not take up a place in Super League, they have decided, even if they win National League One at the end of this season. The Dragons are sixth in the table, but raised eyebrows last week when they took two players from relegated Widnes on loan for the rest of the campaign, with three others turning down the same offer.
One of those who has gone to Doncaster, Gary Hulse, said that the cunning plan was to preserve Widnes' Super League status by helping the Dragons to win their Grand Final but not be promoted.
Doncaster have plans to move into a new stadium at the end of next year, but their owner, John Wright, said that it would be "commercial suicide" to play in Super League at their antiquated Belle Vue ground.
The former Great Britain hooker, Lee Jackson, is retiring after helping York into National League One. Jackson, 36, was a member of Leeds' Challenge Cup-winning team of 1999 and won 17 Great Britain caps from 1990 to 1994.
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