Cass said he didn't believe having two tests at Eden Park meant there was diminished interest from fans in buying tickets for the Blues. Tickets for the match on June 7 cost up to $129.
"It will get to a situation soon where that will be the only opportunity to see the Lions. We've already got a crowd that will be fantastic for that game.
"To see history in the making, and the first game between the Lions and a Super Rugby team... we're totally confident it will sell out."
Eden Park has a capacity of just under 50,000.
Cass said 93 per cent of the available tickets for the 10 games in the series had been sold.
"It's a little over a month until kick off and demand has been fantastic."
Delivery of the tickets begins on Wednesday, a month out from the opening match of the tour between the tourists and the New Zealand Provincial Barbarians in Whangarei on June 3.
More than 98 per cent of the tickets available for the tour were sold the last time the Lions toured here in 2005, with 355,000 of the 360,000 available being snapped up.
According to then New Zealand Rugby Union's 2005 annual report, the last Lions tour 12 years ago saw the union bank $20.4 million of profit.
In the report it is estimated that "foreign exchange gains" generated $120 million for the New Zealand economy with a total benefit of $250 million as a result of the tour.
Cass said he "wouldn't want to talk specifics" on a projection for how much money this year's tour would generate for New Zealand Rugby.
"But it's obviously a one-in-12-year opportunity off the field as well as on it."
About 20,000 fans are expected to travel to New Zealand to watch the Lions play 10 games, including three test matches against the All Blacks at Eden Park on June 24 and July 8 and Westpac Stadium, Wellington on July 1.
Grandstand tickets for all three tests have sold out, as have those for the Crusaders and Lions match at AMI Stadium in Christchurch. Tickets for matches featuring the tourists against the Maori All Blacks, Chiefs and Hurricanes are limited and cost up to $129 a pop.
Packages still on offer include a deal for fans willing to pay $1600 to enjoy the hospitality of The Platinum Club described on the All Blacks Hospitality website as a "magnificently themed, dedicated hospitality facility, uniquely and exclusively developed" for the Lions series.
The package consists of a four-course meal, drinks, entertainment, a souvenir gift and Category A match tickets.
Meanwhile New Zealand-bound Lions fans are facing huge surges in accommodation prices, including one motel seeking a nightly rate of seven times its normal charge.
A Wellington motel, Fernhill Motor Lodge, is charging $1000 a night at the time the city hosts the second test, compared with a regular rate of $135. The Quadrant in Auckland CBD is seeking $1125 on the night of the first test, more than three times its room rate the following week.
A premier, two bedroom "room with a view" at The Quadrant will set you back $1125 for the night of June 24, according to Expedia. The same room is available for $369 per night, a third of the price, just two nights later.
AA general manager of travel and tourism Grant Lilly said that while accommodation rates are under pressure as a result of strong demand during the tour, these skyrocketing prices were a cause for concern.
