The Leicester Tigers duo have been named alongside Tigers teammate Geoff Parling in the starting XV for the second Test in Melbourne on Saturday (kick-off 11.05am BST). Tom Croft and Dan Cole are among the replacements.
They will become the first brothers to start for the Lions in a Test match since Gavin and Scott Hastings in the final match against Australia in 1989.
Ben, who replaces Mike Phillips at scrum-half for his first Lions Test start, says: “It means the absolute world to be playing alongside my brother. To be doing it in a Lions jersey is so rare, I am not bored of talking about it.
"It’s going to be a very proud moment to run out alongside Tom. I just really hope we can both put in a performance.
“The support from back home has been tremendous with messages and everything, and the fans out here have been unbelievable. It’s completely blown me away of what it is to be a Lions player. Saturday really can’t come soon enough for this group of players.”
Tigers director of rugby Richard Cockerill says he is proud of the brothers, and of the three other Tigers in the matchday squad. Geoff Parling makes his first Lions start in the second row while Tom Croft, who started the first Test, moves to the bench alongside his Tigers teammate Dan Cole.
Cockerill says: “It’s a fantastic achievement for Tom and Ben. They are two lads who have come through our system. Ben’s rise through the game has been fantastic and he’s gone on to play for England and now the Lions and Tom, his story just keeps going and going.
“I am delighted for them all. For brothers to play in a Lions Test together is something very special. I am very proud of them both and delighted for the club – it’s an honour they have bestowed on the club and that’s in the history books forever.
“Geoff Parling has done exceptionally well in the four and a bit years from being at Newcastle to here to play for England to be a British Lion. That story in itself is as amazing as Tom Youngs in some ways.
“I am disappointed for Tom Croft not to be starting because I think he’s had a pretty strong tour. There’s still a long way to go and another Test match after this weekend.
“And it’s disappointing for Manu because we know how good he can be. To get an injury on a relatively short tour when you have to make decisions for big games quite early on has been hard.
“Not to make the bench is difficult for him as well but there is still another Test match to come.”
Click here for all the Lions team news ahead of the second Test.
