Scotland suffered a demoralising start to their World Cup campaign as world champions South Africa squeezed the life out of them in Marseille.The Boks kicked off their defence of the Webb Ellis Cup with an 18-3 victory after two tries from Pieter-Steph du Toit and Kurt-Lee Arendse in the third quarter took the game away from the Scots, following a tightly-contested first half.The defeat leaves Gregor Townsend's side with no margin for error in their remaining three matches against Tonga, Romania and Ireland if they are to qualify for the quarter-finals.The two sides went into the tournament in confident mood following encouraging summer campaigns which left the Boks ranked second and the Scots fifth in the world, but with Ireland – the top-ranked team – also in Pool B, the pressure was on both nations to start with a victory.The Springboks started in more assured fashion and had a chance to get the scoreboard up and running in the 11th minute when the Scots were deemed to have collapsed the scrum, but Manie Libbok hooked his penalty wide from 40 metres.The South African stand-off made no such mistake, however, when presented with another opportunity two minutes later after Finn Russell was penalised for a deliberate knock-on as he sent his kick soaring between the posts from a central position 35 metres out.Tempers flared on the side of the pitch just after the midway point in the first half after Damian de Allende was slammed into touch but referee Angus Gardner – after reviewing the skirmish – spoke to four players, but decided no further action was required.Libbok doubled the Boks’ lead to six points shortly afterwards with another penalty after Sione Tuipulotu failed to release.After South Africa lock Eben Etzebeth