Yousuf scored his third successive score of over 50 runs and remained not out on 58, his 56 th ODI fifty. He has so far made one hundred and two fifties in the series.
Chasing a modest target of 198, Shahid Afridi opened for the first time in the series made a whirlwind 32 off 18 balls whereas his partner Yasir Hameed replacing Imran Nazir could score 18 from 46 balls. Younus Khan also made a brief stay and made only 10 and Pakistan were reeling at 68 for three when experienced Yousuf and captain Shoaib Malik came to their rescue.
Both batted sensibly and carried the score to 147 when Shoaib was dismissed for 42. He faced 62 balls and hit two fours and one six.
However, Yousuf continued his calm and steady innings and with Misbah-ul-Haq steered Pakistan to victory with 11 balls left.
Misbah contributed an unbeaten 29 off 32 balls with two fours and one six.
Albie Morkel claimed two wickets for 30 and Shaun Pollock and Makhaya Nitni took one wicket each.
Shahid Afridi for his allround performance was declared man-of-the-match. He made a breezy 32, grabbed three wickets and took two catches.
Earlier, Winning the toss, captain South Africa Graeme Smith chose to bat first and opened the innings with Hershelle Gibbs to give a 43-run stand. However, other batsmen could not contribute useful scores except Justin Kemp, who made 42 off 74 balls with two sixes. Smith was the top scorer with 48 off 68 balls with five fours.
Pace bowler Iftikhar Anjum and leg-spinner Shahid Afridi captured three wickets each for 33 and 37, respectively while Umar Gul claimed two for 25 and left-arm spinner Abdul Rehman took one wicket.
Man Of The Match: Shahid Khan Afridi