London - England great Geoffrey Boycott believes the star men in two "wobbly" batting units could decide the fate of the upcoming Ashes series in Australia.
England are heading 'Down Under' with a top order where only opener Alastair Cook and captain Joe Root are proven performers at Test level.
But Boycott reckons the hosts' batting is as dangerously reliant on opener David Warner and skipper Steve Smith.
"If England are to do well it's vital the two main batsmen, Root and Cook, play well. Absolutely vital," Boycott said Friday.
"Both sides have wobbly batting units," the 77-year-old former Yorkshire and England opener added in a conference call with reporters.
"Even Australia only have two quality players: Warner and Smith...Both sides depend on two batsmen."
As for the bowling Boycott, an Ashes pundit with broadcaster BT Sport, believes Australia have the edge in raw pace over an England attack that will be headed up by the experienced pair of James Anderson and Stuart Broad.
But with injury-prone Australia paceman James Pattinson ruled out of the series before the opening ball of the first Test at Brisbane on November 23, there are doubts over whether the remainder of the home quicks will be able to last the course of a gruelling campaign.
"If everyone stays fit, Australia are definitely favourites," said Boycott. "The crucial question is which of the bowlers is going to stay fit for five Tests in seven weeks?
"If one of the other side's best bowlers break down the advantage turns around."
England, however, could be without key all-rounder Ben Stokes for the whole series.
Stokes, England's vice-captain, was suspended from international duty following an incident outside a Bristol nightclub in September.
He remains under investigation after being arrested on suspicion of causing actual bodily harm and will not fly out with the rest of the England squad on Saturday.
Stokes, who has a broken finger, is still a member of the tour squad as he and England wait to discover if the 26-year-old will face criminal charges.
"I think we've got to accept the home side in recent times wins a high percentage of games," said Boycott.
"On top of that is the Stokes issue. Before that I thought Australia were 55-45 to win, maybe 60-40, mainly because if Mitchell Starc and Pat Cummins stay fit they have more pace."- 'Paper doesn't win Tests -
He added: "With Stokes in the side the difference between the sides wasn't as great deal. He gives England great balance...So I go with Australia on paper.
"But you have to remember paper doesn't win Test matches."
England suffered a humiliating 5-0 series loss on their last tour of Australia in 2013/14, but Broad -- targeted by fans and opponents after refusing to 'walk' when it seemed obvious he had been caught during a 2013 Ashes Test in Nottingham - still took 21 wickets at just over 27 apiece.
"The last Ashes, Stuart was the one player who got more abuse than anybody," said Boycott. "I remember (Australia coach) Darren Lehmann coming out asking the public to abuse him and they did.
"The kid stood up with fantastic character, bowled his bollocks off."
"It will be demanding and Broad and Anderson have to be at their best."
This year marked the 40th anniversary of Boycott scoring his 100th first-class hundred during an Ashes Test at his Headingley home ground in Leeds.
But perhaps his greatest sustained achievement came when England regained the Ashes in Australia in 1970/71, with Boycott scoring 657 runs at an average of more than 93 including two centuries as Ray Illingworth's side won a seven-match series 2-0.
"That was one of the high points," recalled Boycott. "We played on two result pitches in Sydney and we were better at that than they were, with the ball going through the top.
"You don't get many pitches like that in Australia."