Ireland rugby ace Sean O'Brien has praised Ulster captain Iain Henderson as the man who makes the national team tick when he is on his game.
O'Brien also lauded Jacob Stockdale as "the future" for Andy Farrell's men but warned he needs to work more on defence if he wants to be one of the greatest wingers of all time.
Lock Henderson, 28, took the skipper's armband from Rory Best at the Kingspan after he retired and has racked up 58 caps for Ireland.
O'Brien said: "With his athleticism, physicality and strength, he has a lot of strings to his bow as a rugby player.
"We just need to see it on the big occasions all the time.
"He's the closest player Ireland have, in my eyes, to Maro Itoje, in being physical, fast and getting you over the gain line.
"Hendy is also able to move his feet really late at the line and that gets us out of an awful lot of trouble.
"That's why, when he's on it, Hendy is so hard to handle.
"But he needs to be on his game all the time because in the last year or two, if he plays well, Ireland usually play well. I don't know if he realises that."
Carlow-born O'Brien, 33, said he saw "the real Hendy" when they were part of the same Lions squad on the 2017 tour in the 31-31 draw against the Hurricanes in Wellington.
He said: "Hendy was on fire that night. It was one of the stand-out individual performances, bar the yellow card, of the tour.
"He was manhandling people, and the Hurricanes were a very tough side.
"He wanted to prove a point. He wanted to have a real crack at getting into the Test 23, so he had a lot to play for.
"That yellow card didn't help him, but sitting in the stand that night I thought, 'This is the real Hendy'. This is how good he can be. This is the freak of a player that we know he is. He was awesome that night."
In his new book 'Fuel', O'Brien hailed Stockdale, 24, as being vital to the future success of Ireland and backed him to build on his 90 points from 33 games.
The flanker looked back on the first time he saw him run out at the Aviva, alongside Bundee Aki, when they recorded their biggest winning margin over South Africa in 2017, beating the future World Cup winners 38-3.
He added: "That day marked the arrival of a new wave. As well as Bundee's debut, Jacob Stockdale and James Ryan played their first home Test, having made their debuts on the summer tour to the USA and Japan. Every team is re-energised by new, young players coming through, and that day confirmed what all of us already knew - that James and Jacob were going to be the future of this Irish team.
"I don't think Jacob is the finished article yet by a long shot, but if he gets his defensive stuff sorted, he could be one of the best wingers Ireland has ever produced.
"He has a bit to do, but if he can get that right he'll be phenomenal."