Warne: I can't believe that's out

Cape Town - Former Australia spinner Shane Warne has expressed disbelief over the dismissal of Steve Smith during the first innings of the Test against South Africa in Perth.

Smith advanced down the track and was struck on the pad by a delivery from rookie spinner Keshav Maharaj, umpire Aleem Dar gave the batsman out.

Smith chose to review the decision but the ball tracking system showed the delivery may have clipped the stumps and reverted to the umpire's call.

This has prompted Warne to call for the umpire's call part of the DRS to be scrapped.

Warne said on Channel Nine’s Wide World of Sports: "To me this is a bad decision.

"The DRS system is there to get the right decision. There is an argument that (this delivery) is hitting the stumps and it should be out. 

"But for me, I'd make it this simple: the on-field decision should be taken out of the equation.

"It should be very simple. We know (ball tracking) isn't 100 per cent accurate. 

"Let's say if more than 40 per cent of the ball is hitting the stumps, you're out. If it's less than 40 per cent, you're not out. Irrelevant of what the on-field decision was. F

"I can't believe that's out. It sets a bad precedent for me for the rest of the game that a batsman can run out of their crease on a low pitch and be given out."

Former Australia captain Ricky Ponting took up a contrary position on the issue as he lauded the decision and the DRS system.

Ponting said on BT Sports commentary: "I thought (ball tracking) would say it'd go miles over, in Perth that's your natural reaction when you see someone charge down the pitch like that.

"I actually put my hands up with a gap of about a foot, saying 'that’s going go over by a foot'. 

"But it turns out it was actually a magnificent decision, it was just clipping the stump and that’s all it needs to do."

Former England spinner Graeme Swann declared that while the decision was a shock to the system he believes it was the correct one.

During his commentary stint with Ponting Swann said: "It was a shocking because you just don't see things like that, you don't see guys go down the wicket and get given out.

"So it's a brave decision from the umpire but can you see why it was given when the evidence proves it would have hit the stumps. 

"It’s the game moving forward and batsmen will have to adapt and accept that their stumps are now a bigger target because of DRS. 

"It only takes two per cent of a ball to knock off a bail off, so why do you need 50 per cent or more to get an lbw?"