Despite much speculation that Henry would lose the All Black coaching job to coach Robbie Deans, he was retained on a contract for the next two years, later extended to include the 2011 World Cup. He immediately stated that he would retain McCaw as his captain. Robbie Deans instead signed with the Australian Rugby Union, becoming head coach of Australia. In Deans' last season (2008) as Crusaders coach they won the Super Rugby title for the seventh time. Ireland and England toured to New Zealand in June 2008 and the All Blacks came away with a hard-fought win against Ireland, and two comfortable victories against England. McCaw tore a ligament in his ankle against England and missed the start of the Tri Nations.
In 2008 a fourth Bledisloe match was played in Hong Kong with the intention of expanding the game of rugby and in a close 19–14 game McCaw scored the match winning try. The Grand Slam tour to the United Kingdom and Ireland resulted in victories over Scotland (32–6), Ireland (22–3), Wales (29–9) and England (32–6). During 2008 McCaw won every test he captained and a total of 26 out of 28 games he played in at all levels. The All Blacks won 13 of a record 15 tests, retained the Bledisloe Cup and Tri Nations Trophy, completed the Grand Slam and reclaimed the world No. 1 ranking from South Africa.
McCaw finished 2008 by making his debut for the Barbarians against Australia at Twickenham in an 11–18 loss.
McCaw predominately played at openside flanker, although he has played in the other "loose forward" positions of blindside flanker and number eight for the Crusaders. The openside flanker binds to the side of the scrum farthest from the touch-line and is usually one of the first players to reach a breakdown. In 2008, McCaw told the IRB: