Replacement first-five Mitch Hunt landed an 83rd minute drop goal as the Crusaders snatched a 25-22 victory over the Highlanders in their Super Rugby derby in Christchurch.
The result means the unbeaten Crusaders have all but sealed top spot in the New Zealand conference.
However there will be concern in both camps, and from All Blacks coach Steve Hansen, after second-half injures to Ben Smith and Ryan Crotty.
Highlanders fullback and captain Smith, playing his franchise-record 128th game, left the ground for a concussion test and never returned.
Crusaders midfielder Crotty suffered rib cartilage damage and was escorted off, with coach Scott Robertson saying Hansen would likely have to replace him for the opening test of the Lions series on June 24.
Smith is also now in major doubt for the Lions series after missing several games already this season with concussion issues.
Down 22-19 with four minutes remaining Hunt slotted a penalty to bring the hosts level before nailing the winning drop goal.
It was a 14th successive win for the Crusaders, who were also unbeaten in 13 games in their title-winning 2002 season.
The Crusaders got tries to halfback Mitchell Drummond, winger Seta Tamanivalu and flanker Heiden Bedwell-Curtis, as well as two conversions from first-five Richie Mo'unga.
All Blacks winger Waisake Naholo scored two opportunist tries early in the second half for the Highlanders, while Richard Buckman also scored a try and first-five Marty Banks added a penalty and two conversions.