London - Australia great Glenn McGrath believes the form of England spearhead James Anderson could determine the course of the Ashes.
Australia hold the urn but head into Thursday's opening Test at Edgbaston looking for their first series win in England since 2001.
Anderson, 37 on Tuesday, has been battling to overcome a calf injury but McGrath believes he could have a huge impact on the five-Test series if he stays fit.
"On home soil with the Dukes ball, he's the best in the world bowling in those conditions," McGrath told the Sun in an interview.
“He is a big player and if he has a big series for England, Australia will find it tough. If Australia bat well and can get on top of him, that'll make a massive impact on their chances."
The 49-year-old McGrath, working with online trading broker ThinkMarkets to encourage more young people to get into sport, added: "But Jimmy is on his way to 600 Test wickets, which is absolutely incredible."
Anderson is now just 25 wickets shy of becoming the first fast bowler to take 600 in Tests, having surpassed former paceman McGrath's haul of 563 against India last September.
"Jimmy’s got the record now and it won't be beaten," said McGrath.
"For a fast bowler to beat whatever record he sets, they are going to have to play 150 Tests-plus."
This season's Ashes is being played with last year's Dukes ball, which has a bigger seam than the one now in use for the 2019 English domestic season.
While that should benefit both Anderson and new-ball partner Stuart Broad, six-time Ashes winner McGrath thinks the 2018 Dukes will aid Australia's attack as well.
"Pat Cummins will bowl really well with it and if Mitchell Starc is swinging that new ball 150km/h-plus and bowling attacking lengths, he's a handful for anyone," he said.
"It's going to be whether our batsmen have learned and adjusted from last time they were here, when they just went too hard at the ball."
Australia have won just three of their past 19 Tests in England including the match at Edgbaston in 2005, when McGrath was ruled out on the morning of the match after injuring his ankle treading on a stray ball during fielding practice.
While the former paceman refused to give one of his trademark Australia whitewash forecasts, he said Tim Paine's men could retain the Ashes.
"Teams around the world are becoming stronger at home and worse away. That is a massive concern," he said.
"But having been here for the World Cup, a lot of Australia's players have been able to adapt and adjust to conditions, to play on the pitches and get a little bit of a feel for everything.
"We have got the players to do it. But they are going to have to be on the top of their game if they are going to compete with England in their own conditions."