Blues coach Tana Umaga has gambled with a surprising new halves pairing for Friday night's blockbuster against the Crusaders in Christchurch.

Despite getting his coaching tenure off to a dream start with a 33-31 defeat of the defending champion Highlanders, Umaga has dropped promising pairing Bryn Hall and Ihaia West.

In come Tasman halfback Billy Guyton and former Melbourne Storm junior Matt McGahan, who will have the responsibility of directing traffic against a Crusaders side smarting from an opening round loss to the Chiefs.

He has also brought in former All Black Rene Ranger at outside centre in place of Japan international Male Sa'u, captain Jerome Kaino returns from suspension to take the No 6 jersey off Joe Edwards and hooker Quentin MacDonald comes in for last week's stand-in skipper James Parsons.