The hard-hitting Williams sisters are expected to go easy on a pair of All Blacks brothers when they line up in a charity match.

Serena and Venus Williams will play Ardie and Julian Savea in Auckland tomorrow afternoon, to raise cash for Kaikoura.

It's close to selling out, meaning a possible windfall of about $70,000 for the quake-hit town.

The match has been arranged by ASB, whose head of sponsorship Mark Graham said with two of the greatest tennis players ever in the country, it just felt right to do something for Kaikoura.

"It's a small token for what is needed, but hopefully it can bring some cheer."

He believes the All Blacks siblings will be able to hold their own.

"Let's maybe not get too carried away. They're not going to exactly be pushing the Williams sisters that hard, but they know how to swing a racket, they're going to have fun on the court, and we'll mix things up a little bit to make sure it's a nice, fair contest."

Tickets are $30 dollars, plus booking fee, and are available via Ticketek, but there aren't many left.