The brewer - represented by DB Breweries in this country - is confident World Cup rights managers IMG will blow the whistle if its future ads go too far.
Heineken is an official sponsor of the tournament at a global level, while Steinlager is a sponsor of the All Blacks team.
This means it can use its association as the All Blacks' official beer, but it cannot claim any association with the Rugby World Cup.
"I think it is pretty close to the wire and we will make sure they don't step over that line," Rene de Monchy, consumer marketing manager for DB Breweries, said.
The campaign harks back to 1987 when Steinlager came in a white can. A 90-second advertisement launched three weeks ago focuses on four All Black fans through past World Cups. One of the fans uses a white can as a lucky charm.
The creative director who made the commercial - Toby Talbot - said it had been made with input from Lion Nathan lawyers, because of Heineken's rights as an official sponsor of the tournament.
"Nobody wants to spend a lot of money on a commercial then it cannot be played," he said.
Steinlager has been a key sponsor of the All Blacks for 25 years.
Heineken's de Monchy was surprised how close Lion Nathan had gone.
"It is closer than I expected. I would have thought they would have gone more to pride in the All Blacks as opposed to trying to get to the event," he said. Heineken will have a monopoly on beer television advertising around World Cup games.
The Heineken television commercial screening globally was filmed in New Zealand, while the company would launch a local campaign promoting responsible drinking.
Steinlager is confident its marketing - through the white can campaign and beyond - will lead to more sales.
"I'm confident that we have the best property," Todd Gordon, marketing manager for Steinlager, said.
"Our view is that people will be passionate about the All Blacks, not about the tournament," he said. In three weeks it has sold 2.1 million cans wholesale of the 3 million run for the white can product and expects a second run soon.
Consultant James Bickford, of Interbrand, said activity this year marked a battle between a local and global brand, and there was no reason why Steinlager would not be successful despite Heineken's campaign.
Senior marketing lecturer at Auckland University, Mike Lee, said Steinlager's advertisement appeared to be within the terms of its restrictions under the Rugby World Cup Management Act.
