Lions coach Warren Gatland believes "world-class" Johnny Sexton will bounce back from injury but warned that he needed players who could "last for the six weeks" in New Zealand.
The Ireland out-half has played just 75 minutes in a green jersey since last year's Six Nations, after shoulder surgery ruled him out of June's tour to South Africa and hamstring trouble cut short his November series.
A calf injury sustained while playing for Leinster in the Champions Cup draw in Castres has put Joe Schmidt's first-choice No 10 out of Ireland's Six Nations opener against Scotland on Saturday.
The Lions begin their tour Down Under against New Zealand Barbarians on 3 June and conclude with the third Test against the All Blacks on 8 July.
The 31-year-old started all three Tests in the victorious series against Australia in 2013 but he will need to prove his fitness to make the plane to New Zealand.
"We're well aware of what a world-class player he is. He's very important to Ireland," Gatland told RTÉ Sport.
"The hardest thing about the Lions, it's potentially going to be a tour of attrition. You've got five Super rugby sides, the Maoris and three Tests.
"So you're looking for players to go there that can hopefully keep their bodies together and last for the six weeks.
"I'm looking forward to Johnny hopefully getting back, getting fit and taking some part in the Six Nations.
"A number of players have had injuries. We know how tough the game is at the moment. It's incredibly physical, particularly if you're an out-half. A lot of opposition teams come down your channel.
"Once he gets his body back right and fit... a lot of those world-class players can cope with missing a number of games and slot straight back into a side, and I'm sure Johnny will be able to do that for Ireland."
On the day that Montpellier Francois Steyn had his four-week ban for a high tackle on Sexton upheld, Gatland said that the onus was on players to respect the new, stricter enforcement on tacklers making contact around the head or neck.
"It's going to be interesting this weekend. We're all pretty aware of it," he said. "World Rugby have come down hard on bringing the tackle down.
"There's a real concern of safety and the game has become incredibly physical.
"I noticed that even from the experience from 2009 to 2013. The Lions is a benchmark. Every four years you can gauge how physical the game has got and I noticed there had been quite a significant jump in the physicality.
"Player safety is paramount and players are just going to have to refocus on their tackle technique and bring their tackles down, make sure they don't go too high around the shoulders or make contact with the head.
"It's going to take a few of them to take a few weeks to adjust and hopefully we don't end up with too many yellow and red cards in the opening round of the Six Nations.
"Those sort of things do spoil the game so there's a responsibility back on the coaches and players to make sure they adhere to the new policies."
The Lions supremo will attend Ireland's trip to Murrayfield on Saturday, before flying to take in Wales (the employers he is on sabbatical from) against Italy in Rome on Sunday.
Having spent time with the Ireland camp this week, Gatland revealed that he discussed last November's first ever win over New Zealand with fellow Kiwi Schmidt and said it it would be a source of inspiration in seeking a first Lions series triumph over the country since 1971.
"We spoke a little bit about Chicago. A great first half, the All Blacks came back and they showed some great character in terms of the try that Robbie Henshaw scored and then going on to finish strongly," said Gatland.
"It was a good template to be able to handle the pressure and go on to win.
"We had a chat about that performance and result and how important it was, not just for Ireland, but for everyone to get a bit of confidence and to know that potentially the All Blacks are human and if you put them under some pressure they can make mistakes."
Live Six Nations coverage of Scotland versus Ireland on RTÉ Two from 1.30pm on Saturday (KO 2.25pm) and live radio commentary on RTÉ Radio 1’s Saturday Sport programme from 2pm.
Live coverage of Scotland v Ireland in the Women’s Six Nations on RTÉ Two from 6.30pm (KO 6.35pm) on RTÉ 2, with live radio updates and reaction on an extended 2FM Game On programme at 7pm.
Live coverage of Scotland v Ireland in the U20's Six Nations on RTÉ Two from 8.15pm (KO 8.30pm)
