Former Australia opener Justin Langer is expecting England to provide a stiff challenge during the Ashes.
Langer retired from international cricket after the last Ashes series Down Under, which Australia won 5-0.
England, however, are back in possession of the urn following a 2-1 triumph on home soil last year.
And Langer, who has recently worked as Australia's batting coach, feels the tourists' brain trust of captain Andrew Strauss and team director Andy Flower will ensure a competitive renewal, starting in Brisbane on November 25.
"I know Andrew Strauss very well (from their time together at Middlesex) and I rate him extremely highly," Langer told Sky Sports News HD.
"That makes me a bit nervous - the strength of leadership in Strauss and Andy Flower is a very important part of any successful team.
"We are going to have to make sure we get on top of Andrew Strauss early because he was the X-factor in the last series."
Langer also believes it is only a matter of time before England batsman Kevin Pietersen returns to form.
Pietersen will start the Ashes without a Test century for 20 months and was dropped for the limited-overs matches against Pakistan at the end of last summer.
He has since spent time in South African domestic cricket attempting to rediscover his touch with little success.
"He might not have a weight of runs behind him in the short-term but he's got an enormous weight of runs behind him if you look at it from (a long-term perspective)," added Langer.
"He's an outstanding player, there is no doubt about that.
"While we might downplay the fact that Kevin Pietersen hasn't had a great 12 months, or whatever the statistics say, we know he's a very dangerous player. We are aware of that."