Pietersen has hit two one-day half-centuries against Australia

Pietersen's two one-day half-centuries against Australia helped earn him a likely Test debut at Lord's.

"It has been good to see Pietersen before the Test match. I think he is very much suited to the one-day game.

"We have seen a few things in the last few weeks to enable us to make a plan up of how to bowl to him that we think will be successful," said McGrath.

"It will be interesting to see how he goes on at the longer format of the game.

"The fact that he averages 50 in first-class cricket shows that he can handle it pretty well."

There is a theory Pietersen is weaker playing on the off side, and McGrath admitted: "I am sure we will work out where he doesn't like hitting the ball and try to keep it there.

"We have picked up a few things in the one-dayers, certain shots he plays, and I think we've got a pretty good game plan ready to go from what we have seen."

Strauss is a key to their line-up - in the one-dayers we've done well against their opening batsmen Glenn McGrath

While Pietersen has grabbed many of the pre-Test headlines, McGrath repeated his assertion that paceman Steve Harmison may hold the key in England's quest to regain the Ashes.

"Harmy to me is a massive key for England. If they are to do well against Australia, then he has to perform at his best - maybe the best he has bowled in international cricket," he said.

"I thought he started the one-day series very well but in the last few games he didn't seem quite the same so whether his confidence has dropped a bit, I am not sure.

"But for me, he is a huge key for England and a lot rides on how he performs in this Test series."

The time is right for Pietersen - we must take the battle to the Aussies! From NB Have your say on TMS

McGrath has already set his sights on dominating Andrew Strauss and Michael Vaughan in this series.

And either man could provide the 35-year-old pace bowler with his 500th Test wicket, making him just the second fast bowler to pass that milestone.

"Strauss is a key to their line-up. In the one-dayers we've done well against their opening batsmen," he added