No old pals' act for Lion kings Vunipola and Furlong
Across the St James' Park pitch tomorrow there will be Lions battles going on.
If a Test team was being picked this summer, it would be dominated by players from Leinster and Saracens, who also enjoyed the highest representation when Warren Gatland's side secured an unlikely draw in New Zealand two years ago.
Much of the focus will centre on Johnny Sexton and Owen Farrell, the talismanic out-halves who are so good the tourists were compelled to play them together when rescuing the series against the All Blacks.
Seán O'Brien will have a big say on matters, Liam Williams could cause major damage against James Lowe, while Jamie George's supply out of touch to Maro Itoje and George Kruis will be a factor.
However, the tight five may yet have the biggest say, and the compelling figures of Mako Vunipola and Tadhg Furlong could have the biggest influence of all.
No two players epitomise the modern prop more than the Lions' starting front-rowers from 2017.
Furlong excelled on that tour, while Vunipola's physical contribution and ball-handling was exceptional.
Off the pitch, they worked closely on scrum strategy and spent time together during the quieter moments, while on it they worked with and against each other in live scrummaging sessions.
Last season, Furlong had the upper hand when their paths crossed, but the England star won man of the match when Eddie Jones's men ransacked Dublin in February.
Whoever gets on top tomorrow will have a big say in the destination of the title.
"He has obviously proved to be one of the best in the world, if not the best," the England loosehead said ahead of locking horns with Ireland's tighthead on Saturday.
"Again, that is why you play the game, you want to test yourself against the best.
"It is a great opportunity this weekend and hopefully we can try and nullify some of his impact, but you can only do so much. I am looking forward to a great match-up.
"He surprised me in the way he was such a big guy and his set-piece stuff was solid, but around the park I couldn't believe how hard he worked.
"That is one thing I take from those tours and being around those great players - you are always going to learn, it is just whether you want to.
"He has obviously got all the skills, sometimes you forget he is a prop forward. But I think he never takes away from his bread and butter, which is his set-piece.
"He is very reliable as a player, and when he does come and train he always gives 100 percent. That is the sign of a great player in my eyes.
"Probably where we were closer, was off the field. He is a top bloke and he's very easy to get along with."