Alastair Cook is the best opening batsman in international cricket, says former England captain Graham Gooch.
England skipper Cook hit 263 runs in 836 minutes of his side's first innings in the drawn first Test with Pakistan.
Scored in reply to Pakistan's 523-8 declared, it was the longest ever innings by an Englishman and the third-longest in Test history.
"It was one of the great innings," Gooch told BBC Radio 5 live's Sportsweek programme.
"Ali has always been very mentally strong, his concentration and application have always been there from a young age," added the 62-year-old, who worked as England's batting coach between 2012 and 2014.
"I think Alastair is the premier opening batsman in world cricket and has been for a number of years. He's been playing for nearly 10 years but he's still only 30.
"The best years for a batsman are from 25 to 35, with the really premium years probably from 27 to 33, so he is right in the middle of his best period."
Cook is already England's record run-scorer in Tests, with 9,593 from his 120 Tests, at an average of 47.49, having passed Gooch's previous record of 8,900 earlier this year.
"He should go well past 10,000 runs and really, the world is his oyster," added Gooch, a mentor for Cook since his emergence at Essex.
"I don't think he will have any problems fitness-wise. The only question is whether you can retain your mental stability, that drive and hunger. That tends to go first and then there is danger you get burnt out."
Cook's stamina-sapping innings in Abu Dhabi has seen him rise to eighth in the world rankings for batsmen, with team-mate Joe Root second behind Australia's Steve Smith.
Should play have been stopped for bad light?
England eventually fell agonisingly short of victory in the first Test. Having dismissed Pakistan for 173 in their second innings they required 99 to win but had to settle for a draw, 25 runs short of their target, as bad light stopped play.
Gooch said the umpires' decision to take the players off was "not good for the image of the game".
"You want to be out there entertaining people. Obviously they had taken a reading from the day before and went with that but common sense should prevail.
"In the past the umpires asked the batting side if they wanted to stay on. Obviously England would have liked to. I don't think the average person on the street would understand why they went off."
England head coach Trevor Bayliss says he expects the International Cricket Council to look at ways to avoid matches finishing in such a way.
"At some stage in the future something probably should happen. We are in the entertainment business and the game doesn't go on without the fans," he told BBC Sport.
"But every team has been on both sides of the equation, so everyone's aware of what happens. There are no real arguments."