Ajantha Mendis might have created flutter in cricketing circles with his stupendous performance in the Asia Cup, but the Sri Lankan mystery bowler has failed to impress spin guru Terry Jenner, who pointed out at chinks in his armour.

Jenner, who is credited with grooming Australian spin legend Shane Warne [Images], is surprised to learn that the freaky Sri Lankan spinner does not have a stock ball in his kitty.

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"Mendis needs to develop the stock ball which is very essential for leg break bowlers. When I heard that he doesn't have stock ball, I was amazed," said the Australian great, who is in New Delhi to oversee a bowlers' camp.

"The world's best spinners have a great stock ball. Murali [Muttiah Muralitharan] was one of them. As a coach, we need to teach basics not magic deliveries," he added.

Jenner feels Mendis lacks variety and still has a long way to go to prove his mettle in the international circuit.

"What he is doing has been done before by bowlers like John Gleeson. He is a good bowler but I am doubtful about his success in Australian and South African pitches. He does not have variety in his bowling," Jenner said.

"His carrom ball is not unique; what is unique is his pace. His sudden rise in popularity is because of the fact that most of the world's best spinners have either finished their career or in the twilight of their career.

"In Mendis, people are trying to find out Warne, [Anil] Kumble, Muralitharan, but by doing so they are putting too much pressure on him," Jenner said.

Jenner said young Indian spinner Piyush Chawla [Images] has great potential to be the "next best thing in the world of spin" if he develops his leg-break.

"Don't write off Chawla. He can be the next best thing in the world of spin bowling, but the same issue, he too lacks variety. His wrong ones are very deceptive but he can't bowl two to three wrong ones in an over in Test cricket," he asserted.

"He [Chawla] needs to develop his leg break to be successful in Test cricket."

The Australian also said India Test skipper Kumble has come of age since he first met him in 2003.

"He [Kumble] has done really well in the last couple of years. There's a lot of difference between now and when I met him first in 2003. That time, his job was to contain batsmen, but now he is bowling with the aim of picking wickets.

"I had advised him to change the sequence of his deliveries as he has only three to four balls in his armour and it helped him a lot.

"Both Warne and Kumble's heart are bigger than their bodies."