Berkeley, Calif. – So it's time for the first really huge test for the University of California, as the Golden Bears host the University of British Columbia Thunderbirds in the first leg of the teams' annual two-game series.

This opening leg of the "World Cup" (so named as it was a challenge trophy formed by the now-defunct Vancouver World newspaper, which is like a news website but printed on actual paper), kicks off Saturday at 11am PT at Cal's Witter Rugby Field.

This game is being held two weeks earlier than usual, and that's not necessarily good news to the Bears, as they have really only just started. As the same time, Cal's 79-0 shutout of Cal Poly last week indicates that they might be doing just fine, thank you.

Saturday’s match airs live on Pac-12 Network with cable-carrier credentials also providing access to the broadcast via pac-12.com and the Pac-12 Now app.

Cal is the winner of 11 of the last 15 “World Cups,” The 95-year-old challenge series ended in a split last year when the Bears dropped their home half of the series 19-6 before edging the Thunderbirds 23-21 in Vancouver. On aggregate, then, UBC won the series.

UBC is currently 10-0, including last week's 21-5 defeat of Capilano in BC's Premiership. In fact, Cal is one of only two university teams UBC plays at this level - the rest of their games are against premier club sides in British Columbia, and that includes the vaunted Seattle Saracens, a team the Thunderbirds beat twice in non-league games in November. They have also beaten Capilano twice, Vancouver Rowing Club, Burnaby Lake twice, UBC Old Boys, Meraloma, and the University of Victoria. The last Capilano game and UVic were Premier League games.

So Cal Head Coach Jack Clark, who recently signed an extension with the University, said it's pretty clear this will be a hugely difficult task.

“I’m not sure if there would ever be a good time to play this lot, but it wouldn't be after having only one full match under our belt,” said Clark. “We will need to grow up pretty quickly or we risk a troubling outing. That said, we are grateful for the opportunity to play such a talented team. The burden is on us to give the T-Birds a match.”

The Thunderbirds opened their 2015-16 season at the World University Cup, where UBC defeated New Zealand Universities, 20-10, before going on to place third with an 18-14 victory over Oxford University in the consolation championship.

“It is hard to imagine a UBC team with more firepower and competitive success than this crew,” Clark said. “They have doubled down on their rugby scholarship funding and their talent level has gone through the roof.”

Cal gets loosehead prop Scott Walsh and center Jesse Milne back from injury for the game. Walsh will join hooker Michael Bush and tighhead prop George Vrame in the front row. Locks James Kondrat and Tomas Zerbino will likely be flanked by first-year Bear Thomas Robles and 19-year-old freshman Nic Mirhasem, and anchored by Drew Gaffney at No. 8.

The scrumhalf jersey will be worn by either Eakalafi Okusi or Nicklas Boyer, who is slowly returning to full go from injury. The backline for the Bears figures to include Russell Webb at flyhalf, Milne and Anthony Salaber at the centers, sophomore Jake Goena at one wing after his solid outing against Cal Poly and the final spot at the other wing likely going to Miles Honens, sophomore Zach Tavenner or fellow second-year William Fuller. Harry Adolphus will man the fullback position.

Meanwhile, UBC senior Brock Staller said UBC does not take this game or this rivalry lightly.

"They usually have a sellout crowd and for many of the guys on our team that don't go on to play for Canada, this is really a highlight in their careers," said Staller. "It's an opportunity to play the top program in the United States. We haven't reached our full potential yet but playing against an expansive team like Cal, we can show them how we play. They play a direct style with a lot of structure around their lineouts and scrums and they have the athletes and coaches in place to make it work."