Senior, Willie Poching and Danny McGuire have all been cleared to pay Hull in Cardiff's Millennium Stadium, along with Mark Calderwood, who missed last Friday's defeat by Bradford as a precaution.
Senior was the biggest doubt and some outside the club remain sceptical that his badly twisted ankle will allow him to play. The Leeds coach, Tony Smith, however, was entirely confident about his prospects yesterday.
"It is great news for the players involved and the team," he said. "All three will be available for selection for Cardiff, as will Danny Ward, who missed training earlier in the week.
"Our medical staff have been working intensively this week to get the players right and we are delighted to have them on board for the trip to Cardiff."
Poching, who fractured a cheek-bone last month, might play in head-gear to give the injury some protection, but he has no doubts about playing. McGuire has got over a knock to his shoulder and Calderwood has recovered fully from a dead-leg.
Hull named their 20-man squad yesterday and they have one absentee from their semi-final line-up in Richie Barnett.
The former Gateshead winger has a stress fracture of the foot and has been told that he cannot start running on it until Monday, so has been ruled out. Nathan Blacklock will play.
The match is now a 74,000 sell-out, with the last remaining tickets snapped up yesterday.