Sydney - Former Australia captain Ricky Ponting piled more pressure on under-fire England skipper Alastair Cook on Tuesday by saying he will not improve as a player for the rest of his career.
England's 95-run defeat by India in the second Test at Lord's on Monday made it 10 successive Test matches without victory for the team - their worst winless streak in the format for 21 years.
Cook, 29, has failed to score a Test hundred in 27 innings and has totalled a meagre 129 runs in nine Test innings this calendar year, sparking calls for him to be fired.
Ponting, who retired last year after playing 168 Test matches, said most players find it hard to perform after their first 100 Tests.
"He'll try and find ways to sort of hang on and maintain a certain level," he told the Australian Broadcasting Corporation.
"There's no doubt that the struggles of his team will be having a big impact on the way that he's playing.
"I don't think he's going to get any better as a player."
Former England captain Nasser Hussain has urged Cook to stand down, although immediately after the match he said he had no intention of resigning.
Michael Vaughan, Hussain's successor as England skipper, has also been scathing about the way England have been playing under Cook.
"It's been absolutely pathetic from England," he told BBC Radio's Test Match Special.