Mako Vunipola heaped praise on Owen Farrell as he tipped his Saracens team-mate for future British and Irish Lions captaincy ahead of their tour of New Zealand.
England star Farrell and his 40 team-mates will face world champions the All Blacks in a 10-game tour of New Zealand, starting against the Barbarians on June 3.
Farrell is set to play a key role for Warren Gatland's men, who are looking to become the first Lions team since 1971 to win in New Zealand, and Vunipola is expecting big things from the playmaker.
"Definitely, I think he's got great potential but also he's a great player at the moment," Vunipola said of Farrell's captaincy abilities.
"I think if the coaches need anyone to step up and be a captain for them then he'd do a great job.
"At the moment he's a great leader as it is anyway and for us as a team we're very lucky to have him here and not just here at Sarries but also England as well. He's going well for us and long may it continue."
As for playing alongside rivals from Ireland, Scotland and Wales, Englishman Vunipola said: "It's great.
"Obviously you play against a lot of them throughout the year and to be in and around an environment with them you just want to be trying to find time to spend with one another, get closer and hopefully make some bonds before you start playing games really.
"In those tours you have such a short time to get to know each other and you spend more time really off the field just having chats here and there and going out for coffees."
The Lions will face Blues (June 7), Crusaders (June 10), Highlanders (June 13), New Zealand Maori (June 17) and Chiefs (June 20) before meeting the All Blacks in the first of three games on June 24.