Former England captain Michael Vaughan has urged Kevin Pietersen to embrace his attacking instincts for the Ashes.

Vaughan, who captained the side to Ashes success in 2005 before eventually retiring as a player earlier this summer, does not subscribe to the view that the flamboyant batsman should become more conservative, despite being criticised for two poor dismissals in the first Test at Cardiff.

Instead, the man who handed Pietersen his Test debut believes he should back himself to clear the ropes and make big scores.

Pietersen was particularly criticised for his pre-meditated sweep to Nathan Hauritz, a shot which cost him his first-innings wicket, but Vaughan has backed the South Africa-born player to go after the off-spinner when the sides next meet.

"What we expect from Kevin is for him to play to his maximum ability. He got out playing a shot he'd played before and knocked for one," Vaughan said.

"But what I'd have liked to see was Kevin taking on Hauritz down the ground a few more times and hitting him for six.

"I've seen him do it to Shane Warne and to Murali, so I'd like him to attack a little bit more.

"He is an attacking player; I don't buy the thought that he's a guy who should bat for time.

"As captain I always felt if Kevin could bat for three hours he could take the game away from the opposition. I want to see him continue in a positive vein because that's the kind of player he is."

Flintoff had a precautionary scan yesterday on his right knee, which was operated on earlier this year, and could be forced to sit out the second Ashes Test.

"I think he (Harmison) will play," Vaughan told talkSPORT. "I've a sneaky suspicion Freddie might not be fit.

"I know knees. I've studied knees for ten years because of my own (knee problems).

"But I'd be tempted to play him (Harmison) anyway because I think he could be that bowler that could put the Australians under a bit of pressure."

Vaughan admits he has been surprised by Australia and impressed by their performance as a unit.

"I saw a lot of positives from the Australian side; they were very, very good," he said.

"I didn't think they would be as good as before. They don't have the 'x-factor' players that they did before.

"But what they do posses is a fantastic unit.

"I watched them for two or three days, they are very committed, as you would expect the Aussies to be.

"They'll be very tough for us to beat. We just have to make sure we play that bit better, get runs on the board, get hundreds and make them big."