England second row Maro Itoje could be at the start of "five golden years" as he enters the prime of his career says forwards coach Matt Proudfoot.
Itoje, 26, pressed his case as a possible captain for 2021's British and Irish Lions tour of South Africa with a superb display in victory over Ireland.
"Maro has incredible drive," Proudfoot told BBC Sport.
"I think he can become a lot better. I would say he probably has five golden years still ahead of him."
Proudfoot praised Itoje's desire to improve in the wake of his stellar performance against Ireland.
"Monday morning he was one of the first players I got to see," continued Proudfoot. "He wanted to go through his game, he wanted to know where he can improve, what his focus is for the week.
"When you have a player that is that determined to improve, it is understandable to see performances like that.
"I think there is a lot of growth left in him as a young man."
Itoje and England will face Wales on Saturday knowing victory would ensure them top spot in Pool A and a place in the final of the inaugural Autumn Nations Cup.
Wales ended a run of six straight defeats against Georgia last weekend and Proudfoot says he knows how quickly teams can turn their form around from his time working with South Africa before and during last year's Rugby World Cup.
"From my own perspective, South Africa dropped to sixth in the world and a year later they won the World Cup," he added.
"Once a team galvanises their identity and know where they are going, it is very quick to put good performances back to back.
"When I coached in South Africa we never won in Wales, four years on the trot, I know how tough they are at home."
'No player has been judged for doing either'
As part of the Autumn Nations Cup tournament, England's players have observed a moment pre-match to mark rugby's opposition to racism.
While most players have chosen to take a knee, others have chosen to stay standing.
Centre Henry Slade, who stayed standing, said that he disagrees with some of the politics surrounding the Black Lives Matter movement.
In the United States, some elements of the movement have supported police departments' budgets being cut and funds diverted to social programmes.
"No player has judged another for doing either," said Slade on the decision whether to take a knee.
"I want to get this clear, I 100% do not want to see any racism in any form of sport or life ever, but I just don't agree with some of the political ideology of the BLM and I associate kneeling with the BLM."
Number eight Billy Vunipola has previously explained his Christian faith is behind his decision to stand, while flanker Ben Earl has said he doesn't want to undermine the message from his club side Bristol who have marked the moment in the Premiership by forming a heart formation rather than kneeling.
Slade revealed that Exeter team-mate Sam Simmonds' superb solo try against Harlequins on Friday, and the celebration that followed, sparked debate among the watching England back row players back at the squad's hotel base.
Simmonds, who has missed out on England's squad despite winning European Player of the Year in October, raced in from near halfway before shrugging his shoulders.
"A little bit, I guess," laughed Slade when asked if Simmonds' performance was a source of banter among his England rivals.
"Maybe with his first try and his celebration.
"You can see how quick he is to finish that, not many backs would finish that, he has been a really good player for us and hopefully he can keep pushing on."