Otago captain Tristan Prattley made it back from international duty for the match, but absentees Ant Hancock, James Govan and Donnie MacGregor left little threat up front.
Harley Rodeka moved up to join Regan Coldicott, and both tried hard on scraps of possession. Rodeka's best attack looked promising but was halted by an offside flag.
Injuries during the game also sidelined Seamus Ryder and Jose Cantello to bring more worry lines to coach Richard Murray's forehead.
"The boys battled well," Murray said, and almost got to halftime before Russell Kamo scored the first of his two goals after 42 minutes.
Prattley's presence steadied the backline and, at centreback, a top match by Matt Joy nullified league top scorer George Slefendorfas.
Keeper Oswaldo Rodriguez was also on top form and drew grudging applause from Cantabrians for a string of fine reflex saves.
However, with Andrew Barton spraying passes around, coach Keith Braithwaite's side might have scored more, and All White Aaron Clapham's goal direct from a 55th minute free kick was extremely well hit.
Barton forced keeper Rodriguez into a couple more top saves, then hit the underside of Otago's crossbar, before sliding a pass through for Kamo's last goal.
"Canterbury are a very good side, full of skill and experience," Murray said. "They could go all the way and earn a place in the O-League this year." In contrast, Otago was running on near empty after injuries in the match and youngsters Matt Brook and Southland defender Andrew Ridden came off a very young bench. Aajay Cunningham showed he has the potential to play regularly at the top level.
There were yellow card cautions for Otago's Craig Ferguson, and Cantillo. Ryder was replaced by James Watson.
"Playing Otago is always a tough contest, Braithwaite said.
"They have obviously lost key players, and we have been there ourselves in the past. But like us, they have made up for that with sheer endeavour,"
Next week, Otago plays Wellington in the White Ribbon Cup at Tahuna Park.
ASB Premiership
The scores
• Canterbury United: 3
Russell Kamo 2, Aaron Clapham
• Otago United: 0
• Halftime: Canterbury 1-0
