Hull KR coach Chris Chester has named Albert Kelly in his 19-man squad but insists the Australian scrum-half will not play at Wembley unless he is 100 per cent fit.
Kelly has been a revelation in his first season in Super League and has played a key role in the Robins' run to their first Challenge Cup final for 29 years, but he has been sidelined since the semi-final over Warrington with a knee injury.
The former Gold Coast Titan looks certain to face holders Leeds on Saturday, but Chester admits he is mindful of the experience of another Australian, Gavin Miller, on whose fitness Hull KR gambled the last time they went to Wembley.
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Miller's hamstring injury severely affected his performance and contributed to Rovers' 15-14 defeat by Castleford in that 1986 final.
"It's been mentioned a few times," Chester said. "We know what happened in 1986 and we don't want to make the same mistake.
"Genuinely, if Albert is not 100 per cent fit, he won't play. You can't afford to go into a cup final if someone's not 100 per cent fit. We'll have the team run on Friday and he'll have a fitness test then."
Leeds scrum-half Danny McGuire is expecting and also hoping to face the mercurial Kelly, who has scored 18 in his 23 appearances so far for the Robins.
"We'll prepare for Hull KR's best team and I really hope he plays because I've missed a Challenge Cup final through injury and it's not a nice place to watch a game from," McGuire said.
"I think Albert Kelly has been one of the best overseas imports this year. He has added a massive amount of unpredictability to Hull KR."
Young half-back Matty Marsh, who has been placed on stand-by for Kelly, is not included in Chester's provisional squad while Ben Cockayne and Kieran Dixon are both named as the coach waits to announce which of them will get the full-back spot.
Leeds coach Brian McDermott has included in his 19-man squad forwards Mitch Achurch and Brad Singleton, who did not play in the semi-final win over St Helens but will be hoping to make their Wembley debuts after missing out on last year's final success against Castleford.
The finalists' 19-man squads are:
Hull KR: M Allgood, M Blair, J Boudebza, B Cockayne, K Dixon, J Donaldson, J Green, G Horne, A Kelly, K Larroyer, S Lunt, T McCarthy (capt), J Mantellato, T Puletua, L Salter, K Sio, D Tilse, A Walker, K Welham.
Leeds: Z Hardaker, T Briscoe, K Watkins, J Moon, R Hall, D McGuire, R Burrow, K Leuluai, J Peacock, C Ablett, K Sinfield (capt), S Ward, B Delaney, M Achurch, A Cuthbertson, B Singleton, J Keinhorst, A Handley, M Garbutt.