The formula is to win the collisions up front and take away the time and space that inside backs TJ Perenara and Beauden Barrett utilise to create havoc, according to O'Gara.
"When the ball is in Beauden Barrett's hands, it's not a good sign for any opposition," the former Ireland flyhalf told reporters in Christchurch.
"(But) if you win collisions, if you win the gain line, no matter how good you are as a 10, your time is diminished significantly.
"Our boys have done a great job in that regard in previous campaigns."
O'Gara was not wrong in his summation.
The Crusaders have won their last four games against the Hurricanes, including two regular season matches this season -- although Perenara did not start the game in Christchurch and Barrett did not play.
On all four occasions, the Crusaders forwards won the collisions while the backs were up fast on defence and stopped the 2016 champions from getting any momentum.
Perenara and Barrett played their 100th Super Rugby match together last week against the Bulls and nine-time champions Crusaders had taken notice of how they drove the side around Wellington Regional Stadium.
O'Gara, however, also highlighted that the team could cut loose from anywhere on the field and would need to be totally focussed if they wanted to reach their third successive final against either the Jaguares or ACT Brumbies.
"They have strengths all over the place, they have such talented individuals that you give them time and space and you're going to be under your posts," O'Gara said.
"They have such quality around the park that you would be foolish to focus on one or two, because if you do that they will rip you somewhere else."
(Reporting by Greg Stutchbury; Editing by Sudipto Ganguly)
