Rory Best fears Keith Earls may miss out on a Lions place but has backed Leinster hooker Ronan Kelleher to force his way into Warren Gatland's panel with a big showing against La Rochelle this Sunday.
Gatland will name his 36-man squad for the tour to South Africa on 6 May, with the players set to enter into a bio-bubble for six weeks.
Assessing some of the Irish hopes, Best - who toured twice with the Lions in 2013 and 2017 - said: "Earls is very much someone who will work so hard for the team and I'm not necessarily sure that Gats will overly reward that as much as the likes of somebody like George North eight years ago.
"He loves big impact players, which Earlsy isn't. I'd bring him because I think he's one of the best players I've played with but I'm not picking the team."
The former Ireland captain was more upbeat about the chances of Kelleher squeezing his way in however. He'll face up to Ronan O'Gara's La Rochelle in a mouthwatering Heineken Champions Cup semi-final at the weekend. A big performance in France could make Kelleher impossible to ignore.
"I think Ronan Kelleher has a really big chance," Best said.
"This weekend will be big for him. He was brilliant the last time out against Exeter. You know what? He delivers in the areas Warren Gatland loves. He's big, he's physical and he carries really, really well. If he can have a strong showing in the lineout this weekend and deliver the bits he's good at, I wouldn't be surprised to see him in the squad."
Best also had his say on who will captain the Lions in South Africa. The likes of Maro Itoje and Owen Farrell - who Paul O'Connell endorsed for the role last week - have been mooted, but there's only one man for Best.
"If you look at the guys who are playing the best it's probably Alun Wyn Jones. In terms of... the impact he's having on his team as a leader, that Welsh team never should have been [Six Nations] champions when you looked at them at the end of January but they found something.
"That's what you need from your captain, that he brings people around him through. The big advantage he has is he's used to working under Warren Gatland, they know each other really well, he's captained loads of times under Gats and that's a really big thing to have that coach-captaincy relationship, especially in the short term because... if the captain feels something he's got to feel comfortable that he can say something to the coach.
"And the coach has got to know that if there's something that needs saying it's going to be said to him. That's why Alun Wyn Jones for me is in the driving seat.
"[The Lions captaincy] will be the biggest thing in this person's life ever. It's the biggest honour you're going to get. That moment in time, to be put up there with some of the captains that have captained the Lions in previous years... I've heard stuff about having a squad captain and a side captain, for me I think you make a decision now around who you see as being your Test captain and that's who you pick as your tour captain.
"It's just about having a figurehead who everyone can go and everyone can get behind. It actually will help to bring the squad together as well because if you don't have a figurehead then you potentially have people trying to go, 'look I can be captain', trying to be more vocal that you don't want to be more vocal.
"If Warren Gatland thinks at this point in time that Alun Wyn Jones is going to be his Test captain in that first Test then I'd pick him."
Rory Best was speaking at the launch of Specsavers' Healthy Hearing campaign.
Follow La Rochelle v Leinster (Sunday, 3pm) and Leicester v Ulster (Friday, 8pm) via our live blogs on RTE.ie and the RTÉ News app or listen live on RTÉ Radio 1's Sunday Sport and RTÉ Radio 1 Extra.