DRS not to blame: Clarke

Australia's fighting run chase is precariously placed heading into the final day, with the tourists 6-174 and still 137 runs away from what would be a record fourth innings win.

The good news is the wicket seems to be holding up well for batting, and man of the moment Ashton Agar (1no) is at the crease looking to carry on his momentum and complete a fairytale debut.

Day four once again ended in flashpoint at Trent Bridge, with confusion and inconsistency plaguing the way DRS is used and its potential effect on the Ashes series.

In a match-defining moment in the 59th over with Clarke and Steve Smith looking promising, Clarke stood his ground on a caught behind dismissal, just 24 hours after Stuart Broad refused to walk for a nick to first slip.

Clarke was rightfully given out for edging Broad behind late in the final session - and was the first of three Australian wickets to fall in four overs.
Quick Single: Day four highlights

But the way the process of Clarke's dismissal was handled by both the Australian captain and umpire Aleem Dar highlighted the flaws in the system.

Before giving Clarke out on-field, Dar originally sent the dismissal upstairs to ensure wicketkeeper Matt Prior had got a clean catch on the ball, something which he's entitled to do.

But the fact Dar can check with the third umpire for some things, yet rules don't allow for a howler like Broad's edge to be overturned is a bad look for the game.

As is the subsequent attitude of players, which is to try and get away with what they can from DRS.

"I've said to our team that if you feel you're not out, then back your judgment," said Clarke, who claims he went upstairs because he didn't know if he'd got a touch on the ball.

"If the review doesn't go your way we move on.

"I was given out and had another look when I came in the change room and there was a little spot there on HotSpot. That's the way it goes. That's how the review system operates."

England felt dudded on day two when Agar survived a stumping review on his way to 98, and when the third umpire stuffed up in firing Jonathan Trott lbw.

Australia have copped the raw end of four umpire's calls through the match, with Chris Rogers in the first innings, and Shane Watson and Phil Hughes in the second, all out for line-ball lbw decisions.

For two of the umpire's calls that went against them, Australia also lost a review - even though the margin for error was so slight.

After Clarke and Watson used up Australia's second innings challenges, Agar and Brad Haddin must fight on without any insurance policy for an umpiring clanger.

Clarke was visibly filthy at Dar on day three when Broad stayed in the middle, but refused to buy into debate over whether DRS rules needed to be re-examined.

"It's the same for both teams. We have no excuses at the moment. I'm certainly not going to use DRS as one," he said.

"For us I think we would like to have had a few more wickets in hand.

"I would like to be not out, that's for sure.

"But I'm still really confident that the way Ash played in the first innings, if he can go out and play with the same freedom and confidence, and the experience of Brad Haddin and other batters that are left to come ... we have a chance to win this Test match."