Mako Vunipola renews his rivalry with Tadhg Furlong in Saturday's Heineken Champions Cup final and says the Ireland prop has helped him maximise his own potential.
Saracens and Leinster clash in Newcastle, with the duel between the front rows a key battleground as the English champions attempt to dethrone the current rulers of European club rugby.
The pair had little first-hand knowledge of each other until they were selected for the 2017 Lions tour to New Zealand and went on to start all three Tests of the drawn series.
Vunipola has since established himself as the game's outstanding loosehead and the England star insists it was Furlong who showed him what a prop can achieve.
"Tadhg has proved to be one of the best in the world, if not the best," said Vunipola, who is set to return for Saracens after an ankle injury.
"Hopefully we can nullify some of his impact, but you can only do so much. I am looking forward to a great match-up.
"He surprised me on the Lions tour in the way that 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.
"I thought, 'I'm all right at this', but then you saw what he did and you are like, 'Oh, no I'm not'.
"It gives you motivation to push yourself and that is what you get with good players.
"That is one thing I take from those tours and being around those great players - you are always going to learn, it's just a case of whether you want to.
"He has got all the skills and sometimes you forget he's a prop forward, but that never takes away from his bread and butter, which is his set-piece. Everything else is a bonus.
"He's very reliable as a player and when he trains he always gives 100 per cent. That is the sign of a great player in my eyes.
"Off the field we were close. He's a top bloke and he's very easy to get along with. Front-rowers tend to migrate towards each other anyway. We spent a lot of time together on the Lions tour."
Furlong is equally complimentary about his Saracens counterpart and former room-mate.
"I got on well with Mako. He's good craic. When we were over there we roomed with the props and hookers to try to build relationships.
"I got stuck in a room with Mako a few times, which I enjoyed. He's a pretty laid-back character.
"Mako is world class in what he does; he has had a few injury problems this year but he has come back and looked really fresh," said Furlong.
"His ability to attack the gainline, his ability to bring others into the game, his footwork, late at the line.
"He is a quality player to be fair to him. Sarries use him in set-piece moves and he is a player I enjoy watching."