Billy Vunipola is irreplaceable. Alongside Owen Farrell, he is one of two players the British & Irish Lions could not afford to lose.
News of Billy's injury is a colossal blow, both on and off the field. Not only is he an affable character, but he is also the man who would have brought ballast, an unrivalled carrying ability and an infectious personality to the touring party.
He has played against the All Blacks on four occasions and they would have been on red alert. They would have seen his form in the Six Nations, and how under Eddie Jones he has established himself as a truly world-class player. New Zealand would have had a plan for Billy; he's the sort of player you have to single out with the hope of stopping him in his tracks before he starts getting up a head of steam and causing carnage.
From the Lions' perspective, he is the man you form game plans around, as not only does he punch holes, he also creates them. Against Clermont in Saracens' Champions Cup final win, he was immense. He constantly hammered away at the gainline, but there's more to his game than mere ballast. Both England and Saracens utilise him as a receiver for opposition kicks; he catches them and runs them back, usually breaking the gainline. His has an all-court arsenal.
But even he has struggled with the length and brutality of the current season structure. His knee gave out in November and returned in March and now he requires shoulder surgery. He was clearly struggling against Exeter on Saturday, pausing every now and then to cradle his arm. Only Saracens and he know how long he has been nursing this injury but his words after the Champions Cup final seem even more pertinent.
When asked about what was awaiting him in New Zealand, he answered: "It's a different challenge ... if I actually get on the plane." Maybe he knew at that stage, deep down, that his body was going to kybosh his Lions dreams.
For Billy this will come as a huge blow but aged 24, he has two more Lions tours in him. That will offer little comfort for this crop of tourists.
⚫️The All black's will be waking up like they have just won the lottery⚫️
— Jim Hamilton #1000 (@jimhamilton4) May 21, 2017
The nature of the Lions tour, and the relentless game-on-game schedule means his absence will cause Warren Gatland to re-think his back-row plans as he is down to just one out-and-out No. 8 in Taulupe Faletau. James Haskell's inclusion -- a fully deserved one at that -- means they will now utilise CJ Stander more at the base of the scrum. Haskell can play there, but Stander, with his impressive ball-carrying and handling ability, is now the more likely option at No. 8.
Haskell's presence in the touring party is key. He will bring an energy to the group and a huge amount of experience but this is not a like-for-like replacement.
The onus is now on Faletau as, barring injury, he will start the first Test against the All Blacks at No. 8. The good news for the Lions is the Welshman heads on tour in a rich vein of form, the sort that sees him rightfully regarded as one of the premier back-rows in world rugby.
There had been a suggestion that Gatland was considering trying to shoehorn both Vunipola and Faletau into the same back-row, but the injury has put paid to any such plans. Gatland now faces a difficult balancing act as he attempts to simultaneously wrap Faletau in bubble wrap while ensuring he is match fit on June 24.
Gatland was always prepared to suffer pre-tour setbacks. He expected injuries and suspensions -- the tale of previous Lions tours suggested he would be robbed of at least two players. But Billy is one player he could not afford to lose. The severity of his absence cannot be underestimated.