Cape Town - Australia opener David Warner believes the Proteas deliberately "worked on the ball" to generate reverse swing in the second Test at St George's Park in Port Elizabeth that concluded last Sunday.The South African attack found greater reverse swing, especially on Day 4 when the Aussies collapsed from 126/0 to 216 all out.Dale Steyn, who took 4-55, looked unplayable at times as South Africa won by 231 runs to level the three-Test series at 1-1.Warner, speaking to SkySports Radio, said that while both teams tried to make the ball reverse by throwing it in on the bounce across the outlying wickets, he felt South African wicketkeeper AB de Villiers went a step further."We were actually questioning whether or not AB de Villiers would get the ball in his hand and, with his glove, wipe the rough side every ball," said Warner, who went on to say it was another thing they (Australia) would bring to the attention of the umpires.Warner admitted that teams generally try to throw the ball onto the wickets in order to rough it up, but conceded that South Africa did it "better and more" than they did.Warner's questions come four months after South Africa batsman Faf du Plessis was fined for ball-tampering during the Dubai Test against Pakistan. Television visuals showed Du Plessis rubbing the ball near the zipper of his trouser pocket, after which the umpires changed the ball and awarded a five-run penalty. The third and deciding Test starts at Newlands on Saturday, March 1. HAVE YOUR SAY: Did you notice any untoward behaviour by the Proteas' fielders? Do you believe AB de Villiers is guilty of ball-tampering? Send your thoughts to Sport24.