New Zealand Rugby (NZR) must tread carefully in deciding whether to stick or twist with All Blacks boss Ian Foster after the World Cup as announcing a successor before the tournament would cause distractions, former coach Steve Hansen said. Foster’s contract runs until after the World Cup in France and while the 57-year-old could apply to stay in the job a poor run of form earlier this year has made Canterbury Crusaders coach Scott Robertson the favourite to take over.