Steven Luatua was sent off on the stroke of half-time as Blues suffered a 11th successive derby defeat against Chiefs with a 41-26 Super Rugby loss at Waikato Stadium.
Blues were well in the contest at 15-9 down when flanker Luatua was given his marching orders for a dangerous off-the-ball high tackle on Tim Nanai-Williams, with Hika Elliot rubbing salt in the wounds by scoring moments later.
Tana Umaga's men faced a big enough task with a full complement, so ending their dismal record against Chiefs was always going to be a big ask with 14 men and they slumped to a first loss of the season despite a valiant effort.
Chiefs followed up their impressive 25-14 defeat of Highlanders by running in three tries in each half, while man-of-the-match Aaron Cruden scored 11 points in his 100th Super Rugby game.
Three Ihaia West penalties put a Blues side, fresh from routing Rebels last week, 9-5 up 18 minutes in, but Damian McKenzie finished off a superb move to score Chiefs' second try after Liam Messam crashed over early on.
Cruden converted and added a penalty before Luatua paid the price for taking out Nanai-Williams with a reckless tackle, which was soon followed by Elliot dotting down after the resulting penalty was kicked to the corner.
Chiefs had the game pretty much wrapped up within 10 minutes of the restart, with Lachlan Boshier and James Lowe going over, then Anton Lienert-Brown added another.
Patrick Tuipulotu, Charlie Faumuina and Rene Ranger came off the bench to score tries for a Blues side who made a real fist of it, but the damage had already been done.