England captain Alastair Cook has come under fire from legendary Australian leg-spinner Shane Warne for his style of leadership.
Cook has been labelled "boring and negative" by Warne, who also says his brand of captaincy could cost England the Ashes.
And guiding England to a 3-0 victory in the first of back-to-back Ashes this summer has not prevented Warne from having a fresh dig at the opening batsman.
"Cook can be negative, boring & not very imaginative," Warne said. "I don't like that style of captaincy.
"He needs to be more proactive. If Australia play well, and Cook continues to captain the way he does, I think he will lose the series."
Warne also criticised England batsman Joe Root with Australia's top test wicket-taker claiming he would be "crucified" by Australia's pace attack if asked to open his team's batting.
"We know Root played well at Lord's but I don't think he is an opener because of his technique and I think Australia found him out," he added.
"You can't hang back like that and get stuck in the crease in Australia because of the pace of the wickets.
"He's a good player of spinners and perfectly suited to number six, and in time he can go up to number four and be the main man there.
"It could be crucifying him if he has got to face (Peter) Siddle, (Mitchell) Johnson and (Ryan) Harris on fast and bouncy pitches - he's going to nick off a lot."
Warne also backed Australia captain Michael Clarke following comments made in Ricky Ponting's autobiography, in which the former Australia skipper admitted concerns about Clarke's leadership qualities earlier in his career.
"Michael Clarke, to me, is the best captain in the world at the moment. He's got a lot of imagination, the fields he comes up with to Jonathan Trott or Cook. Cook would never have a leg-slip, bat-pad or leg-gully.
"Michael's very well respected. The best captains, like Mark Taylor & Allan Border, keep stuff in the dressing room. No-one ever finds out about it. That's what good leaders are about. So to hear all this in a book is pretty ordinary."
You can see England's next warm-up match against Australia 'A' live from 11pm on Tuesday on Sky Sports 2 HD.
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