Aided greatly by Usman Khawaja,Ricky Ponting summoned his deepest reserves of skill and focus to give Australia a fighting chance of chasing 310 to square the two-match series against South Africa.Ponting's 122-run union with the sure-handed Khawaja,who was was out to Imran Tahir only one ball before the close,took the tourists to 142 for 3,leaving the match and series deliciously poised with one  day remaining.