Eddie Jones has compared the development of a fly-half to a sushi chef as he urges England prospect Jacob Umaga to accelerate his own apprenticeship.
The 22-year-old nephew of New Zealand great Tana, Umaga has shone during Wasps' advance into the Gallagher Premiership final where he finished a brilliantly-taken try against Exeter.
It was not enough to prevent a 19-13 defeat at Twickenham, but for Jones it reinforced his appreciation for his attacking intuition.
"Number 10s are like sushi chefs. As a sushi chef you've got a lifetime's ambition to be good," Jones said.
"It generally takes you about 10 years before you can start making sushi. Number 10s are the same.
"Umaga's at the start of the apprenticeship and he might graduate very quickly and be able to make sushi at the corner stall and then he might be able to make sushi at a five-star restaurant.
"Look at the example of Daniel Carter. He was at his best at 35, the complete package: calm, takes field goals when they need them, kicks to the corner. And then when there's a line break he's in on it. That's the difficulty of that position."
Umaga has been elevated into England's 36-man squad ahead of Joe Simmonds, the Exeter captain who has been hugely influential in the Chiefs' European and Premiership double.
"I like the way Umaga attacks the line. He reads the game well. The good rugby players are starting to come through, the guys who have a real good feel about the game," Jones said.
"You can't sit back and wait for things to evolve, you've got to be able to go quickly. To do that you need a 10 who's very instinctive. You can't coach them to do it, they just do it.
"You saw that when he scored that try (against Exeter). They got a couple of quick rucks and he just hits the line flat, through the hole, runs the holes, beats the full-back, scores.
"They're the things you can't coach and they're the things you're always looking for in players. It's probably more pronounced now because of the way the game's going.
"You've got this arm-wrestle type around the ruck where there's 80 per cent of the game.
"Then it's one pass and to break that defence down you need really instinctive players that can take the opportunity.
"We can't coach them what to take because we don't know how the defence is going to be. They've got to have the ability to take that. That's why I like Umaga."
Farrell has not played since being banned for five weeks for a dangerous tackle on Wasps' teenager Charlie Atkinson, but Jones has no concern over his readiness.
"The one thing Owen will be is captain, whether he plays at 10, 12 or 13 – I am not sure. That is all to be decided this week," Jones said.
"He is the most professional player I have seen. He is dedicated to his profession and works hard.
"I don't know how many times Jonny Wilkinson has been in to do kicking with him. He is a guy that has this unbelievable desire to win.
"He wants to play for England, he wants to be the best captain we have had and he wants to be the best 10 we have had, or best 12. Wherever he gets selected, he doesn't mind."