With the Lions squad due to be announced on April 19, Warren Gatland and his coaching staff will soon be sat around a table going through each position, one by one, trying to decide who should make up the 37-man squad that will board the plane to New Zealand.
First on the agenda, props. Gatland will likely take six prop forwards with him, three looseheads and three tightheads, and today we are focusing on who might be wearing the No 1 shirt... and why.
The 26-year-old Saracens loosehead, born in New Zealand, raised in Wales and now a proud Englishman of Tongan descent, is an absolute certainty to travel to the land of the long white cloud.
Mako ticks every box. He has previous experience of touring with the Lions, having been selected in 2013, and has grown from a mobile prop who's scrummaging let him down to one of the most destructive front rows in world rugby.
One of the secrets behind his remarkably-intelligent running lines, which he uses to great effect both in defence and attack, comes from his interest in rugby league.
During the Six Nations, Vunipola was restricted to cameos from the bench, with Joe Marler often first-choice loosehead, and it may be a case of history repeated with the Lions - a fresh Vunipola coming on with an hour gone and acting as what Eddie Jones likes to call a 'finisher', offloading the ball and bashing holes through a tiring All Blacks defence.
He averages 8.4 carries a match since the World Cup, but it is the metres made from these carries that stands Vunipola apart from the rest. His extra mobility also makes him invaluable in defence - 14.2 tackles on average per 80 minutes, with a success rate of 91 per cent, is outstanding for a prop.
The Leinsterman is predicted to be the starting loosehead. Tough and durable, he consistently produces a high tackle count and hits a monumental number of rucks.
At 27 he is also at the peak of this powers and has the ability to play on either side of the scrum. All Blacks props Owen Franks, Joe Moody, Charlie Faumuina and Wyatt Crockett will get little joy out of Big Jack, especially as the Leinsterman has a 95 per cent scrum success rate for Ireland off their own feed over the past year and a half.
Of all the possible Lions looseheads, McGrath also guarantees you the most minutes on the pitch - he is averaging just over an hour per game since the World Cup - thanks to his remarkable engine.
The one part of his game that lets him down is a propensity to concede penalties. In the 16 games he has played for Ireland since the RWC he has been pinged 16 times. That's a potential 48 points gifted to the opposition.
What Gatland needs to consider is whether the likelihood of McGrath being penalised is outweighed by the fact he will cause Franks all manner of problems in an area where the Lions needs to gain the upper hand.
If Vunipola and McGrath are considered certainties to earn Lions selection, Harlequins prop Marler is 50/50. As mentioned earlier, he was England's first-choice loosehead during the Six Nations and did a sterling job but does he offer enough around the pitch to secure his flight ticket?
As a scrummager he is undoubtedly world class, although his success rate when packing down for England (89 per cent) is marginally lower than his rivals. His tackle count and tackle completion rates are outstanding (95 per cent), though.
It is in open play that Marler struggles. He averages just under four carries per game, under half that of Vunipola and McGrath.
On the plus side, although going head to head with the likes of Franks and Crockett will be brutal, Marler can claim to have gone nose to nose with the most brutal of them all during the Six Nations - France's 24-stone behemoth Uini Antonio - and emerged with credit.
Marler is also a real character - weirdly likeable - and would make a welcome addition on what is a five-week-long tour.
Currently the favourite to claim the third and final loosehead slot alongside Vunipola and McGrath, 29-year-old Healy's experience will be vital on what is considered the toughest tour of them all.
In fact, if it wasn't for the fact that he has McGrath ahead of him in the Ireland pecking order, Healy would be a regular starter and probably a first-choice Lion. As it stands, he will most likely be an impact sub.
Nevertheless, the Leinsterman's ball-carrying skills, and ability to make hard yards, make him one of the best loosehead props in world rugby and the fact he may struggle to get into the Test team highlights the strength in depth the Lions have at No 1.
His success rate at scrum time is exceptional - 97 per cent - and he concedes remarkably few penalties. Added to this potent mix is the fact he carries the ball more often than even Vunipola.
Rob Evans may only be 24 - which in prop years means he's only just out of nappies - but he has already made a big impression for Wales and thanks to a badly-timed injury to veteran Gethin Jenkins, became Wales' starting loosehead during the Six Nations.
Even back in 2013, he was already on Gatland's radar - called up to train with the Lions ahead of the 2013 summer tour of Australia.
One of his finest hours came against Toulon when representing Scarlets in the Champions Cup in 2015. He was packing down against All Blacks great Carl Hayman, who had Springbok giant Bakkies Botha behind him in the second row, but Evans proceeded to have an outstanding game in both the tight and the loose.
His chances of going on tour are slim, with Vunipola, McGrath, Healy and Marler ahead of the Welshman in the overall pecking order, but if you're looking for a bolter, Evans is thought of very highly by Gatland.
A real enforcer. He won't last a full 80 minutes - in fact, he might not even last a half - but it's a squad game these days. What the 30 year-old will do, however, is give you 50 minutes of blood and thunder, ensuring parity at scrum time.
His stats - carries per game five, tackles per 80 minutes 11.1, tackle completion 88 per cent, scrum wins 90 per cent - are not that great when looked at on a spreadsheet, but Reid is a true Scottish warrior and not shy in fronting up.
Should the 36 year-old earn a call-up, this would be his fourth tour. He even has experience of touring with the Lions to New Zealand having been a part of the disastrous 2005 trip that resulted in a whitewash.
His best days may be behind him but he can still do a job, a very good job. Experience counts for so much in the front row, especially against the All Blacks who are masters of the scrum's dark stars. Jenkins, though, has been there, done that and would be a vital source of information and support to his front-row fraternity.
When it comes to ball in hand, Jenkins's numbers don't stack up when compared to his rivals, but sometimes you just need a prop who can stabilise a scrum and with a 92 per cent success rate on Welsh feed, and only three penalties conceded in the 10 games he has played since the 2015 World Cup, he is Mr Dependable.
Who are the likely looseheads?
Two Irishmen and an Englishman. Jack McGrath and Cian Healy, plus Mako Vunipola.