JOHANNESBURG : Tailenders Wayne Parnell and Rusty Theron snatched an improbable three-wicket win for South Africa in the second Twenty20 international against Australia at the Wanderers Stadium on Sunday.Parnell (29 not out) and Theron (31 not out) put on an unbeaten 64 for the eighth wicket off just 27 balls to level a series which Australia had looked almost certain to win.Australia's youth brigade took their side to the brink of victory but in the end a lack of experience proved costly to the tourists. Teenage debutant Mitchell Marsh hit four sixes in the last two overs to give Australia's innings a late boost, taking them to a total of 147 for eight, which seemed more than enough when fellow teenager, fast bowler Pat Cummins, sparked a South African collapse.Marsh, 19, made 36 off 21 balls on the day he joined older brother Shaun and father Geoff as an international cricketer.Cummins, 18, opened the bowling and dismissed Colin Ingram and JP Duminy as he took two for three in a two-over burst. James Pattinson, 21, kept the pressure on, taking two for 17 in four overs.South Africa were reeling at 84 for seven with only 32 balls remaining when Theron joined his franchise teammate Parnell.There were still 37 needed off three overs when Australian captain Cameron White brought left-arm slow bowler Steve O'Keeffe on to bowl. The left-handed Parnell hit him for a four and two sixes in an over which cost 18 runs.Cummins bowled the 19th over and conceded 13 runs, including two wides. Six were needed off the final over and White turned to David Hussey instead of the inexperienced Mitchell Marsh. Theron the off-spinner's first ball high over midwicket to settle the match with five balls to spare.