With Amla and Rossouw slamming a record 247 runs for the third wicket off just 181 balls, South Africa charging to 361 for five, bad weather delaying the start of play by two-and-a-half hours and reducing the match to 42 overs per side, the hosts were always in control and they duly bowled the West Indies out for 230 in 37.4 overs.
Their batsmen having once again produced the goods, South Africa’s second-string bowling attack were eager to please but, Wayne Parnell apart, they showed that the Proteas cannot be complacent in the field when they get to the World Cup.
Kyle Abbott managed to dismiss dangerman Chris Gayle with the first ball of the innings, the left-hander only getting a thin edge as he flashed at an ill-directed opener short and well wide of off stump. The Proteas had to get the dismissal on review as umpire Sundaram Ravi called the delivery wide.
Abbott continued to spray the ball about, and although he claimed a second wicket with a full, straight delivery that bowled Marlon Samuels for 50, he persisted with banging the ball in halfway down the pitch and went for 59 runs in seven overs to finish a disappointing series for him.
Narsingh Deonarine (43) and Dwayne Smith (31) added 77 at a run-a-ball for the second wicket to repair the early damage, but Aaron Phangiso fooled Smith with the arm-ball to trap him lbw and Deonarine failed to get back in time as Samuels turned down a quick single and was run out in the left-arm spinner’s next over.
Samuels went on to score a quickfire half-century before being castled by what replays suggested was an Abbott no-ball, while Denesh Ramdin made a run-a-ball 40 before being undone by a sharp lifter from Parnell, gloving a catch to square-leg, where Amla moved smartly and dived to take a fine catch.
Parnell would be the best of the South African bowlers by some margin, taking four for 42 in nine overs, while fast bowler Marchant de Lange, who will not be going to the World Cup, enjoyed standing in for Vernon Philander (slight groin strain) and took one for 34 in eight tidy overs.
Although the West Indies’ batsmen never threatened to win the match, South Africa’s bowling was not precise enough for them to be happy with their performance in the field. Even Parnell tended to stick to back-of-a-length deliveries, which will be fodder for better batting line-ups at the World Cup.
Rossouw proved his credentials with the World Cup just around the corner as he lashed a great century, helping himself to a career-best 132 off just 98 balls, with nine fours and eight sixes, and Amla cruised to yet another century, scoring a fine 133 off 105 deliveries.
Rossouw and Amla added 247 for the third wicket off just 181 balls, a record third-wicket partnership for South Africa and equalling their own mark for the best stand for any wicket that they set in the second ODI at the Wanderers.
It was another top-class batting display by the South Africans, even with big gun AB de Villiers having a rest, as they laid a solid platform on a tricky pitch and then launched a spectacular late onslaught.
A couple of wickets had fallen in the first 10 overs as Quinton de Kock (4) and Faf du Plessis (16) fell to horizontal-bat strokes on a pitch that provided enough awkward bounce to make those shots difficult.
Amla once again looked in a class apart as he reached a 49-ball half-century in the 21st over, midway through the innings with South Africa on 109 for two, while Rossouw, who has endured a troubled ODI career thus far, struggled through to his 50 off 60 balls.
But those early miscues all seemed a lifetime ago as Rossouw then blossomed in spectacular fashion, needing just 23 more deliveries to register his second century of the series.
The left-hander raced past Amla and looked every bit a power-hitter as he smashed 82 runs off his last 38 balls.
Amla just kept on amassing runs as he has all series, except in this innings he was able to do it in half-dozens at a time, clearing the boundary six times to go with his 11 fours, showing that even a great batsman like him has had room to improve his game.
The West Indies were bleeding runs horrifically as the sun shone brightest on its way to the western horizon, bathing SuperSport Park in a sepia light befitting a display that was one for the ages.
The last 147 runs of the Amla and Rossouw partnership came off just 69 balls … and that by two batsmen who are not renowned for being big boundary-hitters.
Finishers David Miller (23 off 9) and JP Duminy (18* off 7) were left with only a handful of overs to bat but they collected their share of boundaries as 87 runs were hammered in the last five overs.
With the bounce providing something for the bowlers to work with – which the West Indians failed to do – South Africa’s total was certainly well over par.