Steyn claimed a career-best 5 for 25 as Pakistan was dismissed for 238 in reply to South Africa’s 266 for 5 in which Quinton de Kock, the 20-year-old, scored a maiden century in just his ninth ODI. De Kock, the left-handed opener, may still lack finesse behind the stumps, but his 112 from 135 balls with nine fours and a six left nobody with a doubt about his ability with the bat.
Pakistan appeared to have a decent chance of chasing down the target at the start of the 47th over with Misbah-ul-Haq well set on 65 and the total reading 228 for 5 with 39 runs required from the final four overs. But Steyn claimed three wickets in the over to all but end the match in emphatic fashion.
Morne Morkel clutched a swirling catch on the third man boundary’s edge to remove Umar Akmal, Misbah mistimed a drive to deep midwicket to depart for a finely crafted 65, and Saeed Ajmal was bowled first ball to leave the run chase in tatters at 231 for 8.
Pakistan had opted for a cautious approach but it was painful to watch for the first half dozen overs in which Ahmed Shehzad and Mohammad Hafeez showed no interest in scoring whatsoever, preferring to keep wickets intact.
Steyn was treated more with reverence than respect and his opening four overs cost a mere nine runs. Shehzad, who made such a blazing start in the third match two days earlier, was the epitome of restraint before accelerating to 43 from 59 balls when a swoop from de Villiers at cover left him run out – a desperate lunge saw his bat over the line but in the air.
Mohammed Hafeez missed a straight one from Imran Tahir and debutant Sohaib Maqsood’s sparkling 56 from just 54 deliveries ended with a brilliant, backward-leaping catch by de Villiers at mid off.
Earlier, South Africa’s innings started in positive fashion and promised far more than the final total for most of its duration. Hashim Amla led the way during an opening partnership of 87, full of trademark flicks and searing cover drives, before missing a glide to third man against Mohammad Hafeez and losing his off stump.
Faf du Plessis launched an ambitious cover drive against Mohammad Irfan straight into the air and de Villiers, having shared a third-wicket stand of 69 with de Kock, was caught at cover off the leading edge. It was a brilliant cameo from him, including an audacious lap-sweep against the pace of Irfan.
South African hopes that de Kock might extend his innings into the final stages were ended with a soft catch to mid off but JP Duminy (25*) and Ryan McLaren (28*) posted 52 from the last six overs to ensure the total was competitive, if a little below expectations, at 198 for 2 with almost ten overs to go.
“I’m just so lucky to have Dale in the team,” admitted de Villiers after the match. “He has a killer instinct and the ability to turn a match on its head. But I’m proud of every member of the team. Quinton has a fabulous future ahead of him, it was a tremendous innings, and the whole bowling attack was brilliant in support of Dale.
“I am very proud of winning the series with a match to spare. We had an ordinary series against Sri Lanka a couple of months ago so it’s great to show what we are capable of.”