MUMBAI: South Africa's bowlers at the World Twenty20 need to show an immediate improvement, captain Faf du Plessis said on Sunday after watching them struggle despite the luxury of defending huge scores in their first two matches. 'Our first three overs were very disappointing, obviously there were some really good shots. But we need to be a lot better, we have to improve. As simple as that,' Du Plessis told reporters after a 37-run victory over Afghanistan. 'Our skill levels are just letting us little bit down in the first three or four overs. I think we are little bit soft in those areas.' South Africa came to India as one of the favourites to lift the World Twenty20 title at Kolkata's Eden Gardens on April 3 but the bowling unit has come under fire on the Wankhede Stadium pitch. The Proteas failed to defend a 230-run target against England in their opener on Friday with the opponents chasing down a World T20 record score to win by two wickets. English batsmen smashed the South African bowlers all around the park in the first six overs of power play with heavy dew on the ground and on Sunday Afghanistan, who came through the qualifiers to reach the Super 10 stage, raced to 47 in three overs in drier conditions. Afghanistan were ahead of South Africa's score at the halfway stage on 103 for two but paceman Chris Morris and Imran Tahir pulled the Proteas back. Morris finished with four wickets and Du Plessis felt the others need to take a leaf out of his book to improve. 'It's little bit of a Wankhede issue and the wicket is very good, but it's definitely not an excuse,' the skipper said, adding that he had been worried during Afghanistan's chase. 'Morris showed if you bowl with good discipline and good intensity... there is enough for the bowlers still to bowl well (on this wicket).' Du Plessis hoped his bowlers would fare better with South Africa now moving to the relatively slower wickets of Nagpur and New Delhi, where batsmen might find it more difficult to score freely. 'With the wickets a bit more two-paced it means our bowlers have the skills to adapt and show some variety,' he said. 'Our skills have been found wanting on this pitch.'