Former Australia captain Ricky Ponting believes the forthcoming Ashes series could be the beginning of the end for England batsman Alastair Cook.
Cook, who relinquished the Test captaincy at the start of the year, is England's record runscorer with 11,629 and is showing no signs of being ready to stop as he prepares for his seventh series against Australia.
But Ponting says the 32-year-old may struggle for motivation after this tour.
"I know myself having been through it that when you've played a certain amount of games or scored a certain amount of runs - like Cook - trying to find ways to improve on a daily basis becomes really difficult," said Ponting in quotes reported by the Daily Mail.
"Just trying to hang on and maintain a level of performance gets harder and harder."
England, who hold the urn after their 3-2 success on home soil in 2015, were obliterated by Australia's fast bowlers last time they toured Down Under and Ponting expects Mitchell Starc and Pat Cummins to provide a similarly stern test when the action gets under way on Wednesday night.
"They are going to cause some real problems to the English batsmen and the reason I say that is they have all been around for a little while now, they are fast bowlers who are just about at their physical peak and on their way up," Ponting added.
"We saw what Mitchell Starc was able to do in the last few rounds of Sheffield Shield cricket, taking two hat-tricks in the one game, so he is obviously in some good touch.
"Cummins has been on the park for six to eight months uninterrupted, and is bowling very quick. And (Josh) Hazlewood just seems to get better from series to series."
Source: PA
