Heinrich Klaasen and Rassie van der Dussen scored half-centuries as South Africa eased to a comfortable seven-wicket win over ailing England in Karachi on Saturday to book a semi-final place at the Champions Trophy. South Africa bowled England out for 179 in 38.2 overs after the latter had chosen to bat, before reaching their target with a huge 125 balls to spare following a 127-run third-wicket stand between Klaasen (64) and Van der Dussen (72 not out). They top Group B and join Australia, India and New Zealand in the semi-finals, with the fixture line-up to be confirmed when the latter two meet in Dubai on Sunday. The match was the last in charge for England captain Jos Buttler, who is stepping down from his role after the side lost all three pool fixtures in the tournament. England were already out of semi-final contention going into the game and, after winning the toss, their innings never got going as they played some poor shots on a good batting wicket. “A really disappointing performance,” Buttler said. “We were so far short of the mark there today. It was a decent surface — pretty slow and a bit two-paced. “We’re not going on and making those big, telling contributions which has been a story of this side for some time now with the bat.” South Africa did well to expose England´s desire to chase the run-rate with injudicious shots but also bowled both sides of the wicket and will need to tighten up their lines, whoever they face in the semi-finals. “The wicket was quite slow, slower than we expected,” South Africa stand-in captain Aiden Markram said. “The boys adapted really well and kept trying to hold a length for as long as they could. We took wickets throughout. “We’ve got a great squad with lots of options. Whatever role each individual has, (regular captain) Temba (Bavuma) backs them along with the coach (Rob Walter).” Joe Root top-scored for England with a well-constructed 37 before he was bowled by seamer Wiaan Mulder (3-25), while Buttler managed 21 in his final game as skipper. There was little else to enthuse over for the side, with Ben Duckett (24) and Jofra Archer (25) also managing starts. South Africa lost Tristan Stubbs (0) early in their chase, as he played on to his wicket from a delivery by Archer (2-55). But once Klaasen and Van der Dussen got together they constructed a fine partnership that showed the England batters how to play on the wicket. Van der Dussen´s unbeaten 72 came from 87 balls and included three sixes as he anchored the innings along with the more explosive Klaasen. South Africa will sweat over the fitness of Markram, who left the field with a hamstring injury, ahead of their semi-final, while Bavuma and opening batter Tony de Zorzi missed the game through illness.