A few hundred tickets remain for the visit of the Springboks and there are just a few thousand left for the climactic game of the series against Australia, meaning that for those fans who do not act quickly, the Friday night fixture against Canada will fast become their only opportunity this season to see Gatland's Grand Slammers perform on home soil.
"We have two big home games in the Six Nations this season, against England and Ireland, which will reach capacity very quickly and with the news that each of the SANZAR games has sold so will fans will begin to look at Canada as their last remaining chance to see Wales in action this season," said WRU Group head of marketing Gwyn Dolphin.
"Those that are quick off the mark will still be able to snap up tickets to watch Wales face the World Champions and the Wallabies, but our message is that the Canada game is going pretty well too.
"So if you want to relive the glories of last season's Grand Slam and see Wales perform on home soil, then act now or face disappointment.
"Our new ticket sales policy has meant more and more fans out there have had the opportunity to buy tickets well in advance, and special pricing offering value for money for families for the Canada match has been particularly well received - a family of four can attend that game for as little as £50.
"Fans could be forgiven for thinking that if they leave it late they can still turn up and get a ticket, but things are going so well over a month in advance of the series we would like to warn them that this may not be the case."
The few remaining tickets available to watch the visit of the World Champions in the Prince William Cup, and Wales' climactic clash with the Wallabies are available now online at www.wru.co.uk or via the ticket hotline 08705 582 582; tickets to watch Wales take on the Cannucks on Friday 14 November are also available priced at £25, £15 and £10 concessions.