Alastair Cook may already be breaking England batting records, but there's a lot more to come from the determined captain, Sir Ian Botham told Sky Sports.
The Essex man's 136 not out on day two of the third Test against India took him to 23 international Test match centuries, an all-time England record.
Cook - whose innings also made him the youngest player in the history of Test cricket to make 7,000 runs - has now surpassed Wally Hammond, Geoff Boycott, Colin Cowdrey and current team-mate Kevin Pietersen, who all have 22 five day tons for their country.
The knock, compiled with a mixture of smart sweeping, elegant drives, powerful cuts and a big six down the ground, has also put England in command of the third Test, with the tourists trailing India by just 100 runs with nine wickets in hand.
However, at stumps the focus was on the imperious Cook - and just what he could achieve in the future. Given his mentality, said Botham, anything is possible.
"He's 28 on Christmas Day, and, as David Gower said on commentary, every day is like Christmas Day for him at the moment," said the former England all-rounder.
"He averages over 50 and he's done it in 80-odd Tests. He's probably going to play another 80-odd Tests again, so who knows how many he's going to end up with?
"He's got another dozen Test hundreds in him at least - and I think there'll be more. So who knows? Thirty-five Test centuries? Forty Test centuries? You just don't know.
"His record now is remarkable, but I think there's a lot more to come and that's because of the nature of the beast; he's got a unique mind set, he doesn't get flustered - he doesn't even sweat!"
Botham also believes Cook's attitude, whereby he puts the importance of his time at the crease in terms of helping England to victory ahead of personal milestones, is another key to his success.
"When you get your first 100 that's your first milestone and you think 'great', you're on top of the world and then you get out. But the reason he's so good is that scoring 100 is just like a fifty to most other players for him now," said Botham.
"He's not thinking about hundreds, he's thinking about batting his team into an unassailable position. He'll start all over again tomorrow morning and he'll expect to still be there tomorrow evening. That's the mind-set he has. But that comes through experience.
"He's also developing his game all the time, which makes it harder for the opposition to keep him quiet. He's got all the shots now, he's developing and I think he'll feel he's still got a long way before he's the finished article."
Nick Knight was equally impressed with the England skipper and believes Cook's approach of focusing on one ball at a time, although a simple idea, is essential to his run-making.
"Inevitably people around the world will try to come up with some numbers and ask how great he can be and how many runs he will end up getting but I don't think he'll think like that - and that's one of his great strengths," said the former England batsman.
"Cook's not concerned about how many runs he's going to end up with, he just plays ball after ball, innings after innings. To those who have not played the game, particularly not at the highest level, to hear someone say 'I just play ball after ball' seems a very basic and simple thing to do. In fact, when you're out there, in the heat of the moment, it's a very difficult thing to do.
"People talk about mental strength and what it is - to me that's exactly what it is: the ability to forget what's gone before. He was dropped and had a bit of a working over from Ishant Sharma but he put that to the back of his mind and played the next ball.
"We talk about temperament and it's one of his greatest assets. You run out of superlatives to describe the way he's playing at the moment. He's developing his game constantly but when he's out there he's the height of simplicity.
"I'm full of praise for him because it's incredibly difficult to do what he's doing."
Nick Compton posted his maiden Test half-century was happy to play a supporting role to Cook but Knight says his contribution to the innings bodes extremely well for the future.
"He's got the best seat in the house; he's watching Alistair Cook and developed. And I hope in a few years' time we are sitting here saying exactly the same things about Nick Compton," said Knight.
"He's a lot going for him. He's settled into Test cricket and he gets better every innings. With that half-century he will sleep well tonight and say not that 'I've arrived in Test cricket', but 'I can do this, in sub-continent cricket. Yes, it was against a fairly weary attack. But I can do this'.
"And sometimes when you play Test cricket you have to convince yourself that you can do it. People will tell you, but you have to convince yourself."
Botham added: "Remember this guy is developing quickly. He does not even open for Somerset - he bats three or four - so he is taking a big step up and he is handling it very well."