WELLINGTON, New Zealand (AP) — History has proven flyhalves are keys to success in Super Rugby and this weekend's semifinals will emphasize the point as the four best in the tournament attempt to shape the fate of their teams.

There is no surprise that the best No. 10s in this season's tournament have propelled their teams into the final and those players will now have a major part in deciding which teams advance to the championship match.

The Crusaders and Wellington-based Hurricanes who meet in Christchurch are driven by the current All Blacks flyhalves Richie Mo'unga and Beauden Barrett. Their contest behind forward packs of differing quality will be one of the highlights of the semifinals.

In Buenos Aires, the outcome of the contest Friday between Argentina's Jaguares — playing in a semifinal for the first time — and the ACT Brumbies — seeking their first title in 15 years — will depend on the performances of flyhalves of vastly differing experience.

To some degree the Jaguares owe their best-ever Super Rugby season, their first placing in the South African conference and their 12-5 record so far, to the steadying influence and goalkicking of 30-year-old flyhalf Joacquin Diaz Bonilla.

Despite his age, Diaz Bonilla had played only 10 Super Rugby matches and one test at the start of the current season after recently succeeding Nicolas Sanchez in the No. 10 jersey.

In contrast, Christian Leali'ifano, who is in his 12th and final Super Rugby season with the Brumbies, will play his 150th Super Rugby match and is a seasoned international.

He will leave the Brumbies to play in Japan when the current season ends and will be driven by the knowledge that each he plays now may be his last.

Leali'ifano's career has been tempered by adversity. He was diagnosed with leukemia in 2016 but won his battle with the illness to resume his professional career. Every milestone since has been a bonus.

Leali'ifano, now the Brumbies captain, said he had been humbled by the support he had received as he prepares to become only the second player in franchise history after prop Ben Alexander to play 150 matches.

"The amount of support I've had and messages has been really, really special," he said. "It makes me feel like I've had an impact here and I'm really humbled by that. I love this team, I love this city and it will always be really, really special to me."

The best individual match-up of the semifinals undoubtedly is the one between the Crusaders' Mo'unga and the Hurricanes' Barrett. Barrett is currently the All Blacks' first-choice but Mo'unga has the chance again Saturday to highlight his own strong form as the World Cup approaches.

Mo'unga was instrumental in the Crusaders' quarterfinal win over the Highlanders last week, scoring two tries among 20 points. But has the advantage of playing behind the best forward pack in the competition.

Barrett has had to cope with the often scrappy ball that comes from a weak Hurricanes' pack. While he remains composed under pressure he is inclined when pressed by defenses to make poor tactical choices, over-using kicking options.

The Crusaders realize that curbing Barrett's attacking influence by keeping him under pressure will be crucial on Saturday. Former Ireland flyhalf Ronan O'Gara, who coaches the Crusaders' backs, says that will be part of a larger game plan.

"If you win collisions, if you win the gain line, no matter how good you are as a 10, your time is diminished significantly," O'Gara said. "Our boys have done a great job in that regard in previous campaigns.

"But when the ball is in Beauden Barrett's hands, it's not a good sign for any opposition."

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