The secret to Michael Cheika's success with Australia lies in his ability to scare the wits out of his Wallabies, according to Johnny Sexton.

Where straight-laced Stuart Lancaster keeps England on a tight leash and governs by process, Ireland out-half Sexton revealed Cheika rules by fear, but backs that up with deep-thinking insight and shrewd coaching acumen.

Insipid England bombed out of their home World Cup just 16 days into the tournament, blitzed 33-13 at Twickenham by Cheika's rampant Wallabies on Saturday night.

Lancaster is now fighting for his future, while former Leinster and Waratahs boss Cheika is riding high, less than a year into his first Test-level assignment.

When asked why Cheika is such a proficient coach, Leinster pivot Sexton replied: "Because everyone's probably scared s***tless of him, if I was being honest!

"He knows his rugby as well, he's a very clever guy but he does have that presence where he's a pretty scary guy when you get on the wrong side of him."

Cheika guided Leinster to their first-ever Heineken Cup title in 2009, with Sexton to the fore in that campaign.

The pair have kept in regular contact, just as the affable but focused Cheika seems to have managed with the majority of players he has ever coached.

Sexton hailed Australia as one of the new World Cup favourites after their fine early-campaign form, while also admitting he will aim to meet up with Cheika once the tournament comes to a close.

"I was texting him last week. I still send the odd text to him," said Sexton.

"He wished me luck at the start of the World Cup and I was the same.

"We've always got on very well and I was delighted to see him, he's proved what a good coach he is.

"He's turned around Leinster, he's turned around New South Wales and now he's turned around Australia.

"They look like a really formidable team, they look like one of the favourites to go on and win the World Cup now.

"So fair play to him and hopefully I can catch up with him after the World Cup."