Quokka Sports rises a rung.

But can America's Cup, Olympics help lift webcaster into the big leagues?

Quokka Sports Inc. is speeding toward the America's Cup finals with the wind in its sails, but questions dog the sports webcaster: Can it harness deals for mainstream sports? And if so, will viewers and advertisers follow?

This is crunch time for the San Francisco provider of digital sports entertainment. It has made a name for itself with pioneering web coverage of minor sports like extreme mountain climbing and secondary events like the America's Cup, now approaching its climax.

The company's biggest breakthrough has been landing digital broadcast rights to the Olympic Games, but those only come around every two years.

Quokka's year-end results, announced last week, were impressive, with viewership and advertising revenue up across all its coverage areas. But the company's stock has lagged since debuting in July, and analysts believe the company must win gold at the Sydney Olympic Games, then land a …