LONDON: Shane Watson admits Australia may have to get nasty in the Ashes because their competitive edge has been blunted since they were told to stop sledging.

Ahead of the series in England, Cricket Australia reminded Ricky Ponting's players of their responsibility as role models and warned them to set a good example following several high-profile clashes in recent years.

Watson admitted his team-mates have struggled to find the right balance between being gentlemen and intimidating opponents.

But with England now 1-0 up in the series, Watson believes Australia must do whatever it takes to ensure the Ashes don't end up with the old enemy.

Watson said: "One thing Cricket Australia have said to us is to make sure we know where the line is and don't cross it.

"It is a sticky one because of course the general public in Australia want us to be perfect role models and the hardest thing when you play is to be extremely competitive and not cross the line, in terms of the things the general public don't want us to do like spitting and swearing.

"It is a fine line between being perfect role models and being competitive. As a group we don't want to lose the edge. That is the reason we have been so good in the past because of how competitive we are and we don't take a backward step.

"We have got to make sure we do everything we can to win, in the end, because that is what Cricket Australia and the Australian public do want."

Watson is set to play for Australia against Northamptonshire in a three-day tour match, starting on Friday, as the tourists assess their selection options for the third Test at Edgbaston.

"I play hard and I play fair. I don't want to cross the line in any way but I find that is when I am at my best. That is how I love playing cricket, being very competitive," Watson said.

"They haven't named the team yet but I am fit to play and raring to go. I am very excited."

Watson is in the squad as an all-rounder but also as an alternative opening batsman, despite having only limited experience at the top of the order.

Phillip Hughes has struggled against the English bowlers so far and Watson is confident he could fill in if called upon.

"I have tightened up my technique a little bit more. I always believe I have the game and the mental game to bat anywhere in the top order," Watson added.

"I did have a stint opening the batting for Queensland. It wasn't that successful but things have changed since then.

"The most important thing for me is to get into this tour match, prove my fitness and perform when I have the opportunity."