Former British and Irish Lions stars Brian O'Driscoll and Jason Robinson expect Warren Gatland to select Dylan Hartley should Wales hooker Ken Owens fail to prove his fitness for the tour of New Zealand.
Owens suffered an ankle injury in training and missed Scarlets' Pro12 semi-final win over Leinster, with Lions staff monitoring the recovery timescale of the 30-year-old.
Scarlets coach Wayne Pivac is confident his player will make the trip to tackle the All Blacks.
But should the Wales international find himself sidelined, the candidacy of England captain Hartley, overlooked for the initial 41-man group, has at least two high-profile backers.
"You have to imagine he's in the mix," O'Driscoll, speaking on behalf of the HSBC World Rugby Sevens Series, said.
"No-one else jumps out. I thought a potential Lions bolter was [Ireland hooker] Sean Cronin, because he offered something different to everyone else.
"But it's going to be so attritional that Dylan you would think would be the obvious choice. We'll have to wait and see if [Lions coach] Warren Gatland thinks similarly."
Robinson added: "You don't want anybody to be missing out through injury. But injuries are inevitable. It's what happens. It often does give other guys a chance.
"It'll be disappointing if Ken Owens doesn't make it because he's had a fantastic season. That being said, I'm sure Dylan Hartley would come in and do a good job."
The Lions open the tour with a match against New Zealand Barbarians in Whangarei on 3 June. The first Test against the All Blacks is in Auckland on 24 June.