As part of a Rugby World Cup promotion, Heineken Original bottles displayed flag-inspired designs on their labels, with some bottles including the William Webb Ellis Trophy.
Anyone who had a bottle with a label of the trophy was asked to text a unique code on the back of the bottle to qualify for a chance to win a trip to Tokyo to see the final game live.
Texting the code and thinking nothing of it, Leathem received a phone call from Heineken New Zealand marketing manager Taylor Green last Tuesday to tell her the good news.
"I thought it was a hoax call to begin with, and I told him no way, and he said yes and I could hear the team laughing in the background... I was shaking."
She said she was completely blown away and it took a long time to sink in.
The trip includes free flights and accommodation at the Hilton Hotel for Leathem and a plus-one.
She's taking her friend Craig Sweeny who drove with her to Wellington to pick up her passport in time for the trip. It had to be renewed after Leathem discovered it had expired in August.
The pair will have a free day to explore Tokyo when they arrive on Thursday and then head out on a tour organised by Heineken.
It is going to be filled with lots of exciting activities, including sumo wrestling, Leathem said.
"I'm not exactly a sumo, but we'll give it a go."
On Friday they will be treated to pre-match drinks and nibbles before watching the play-off for third and fourth in the corporate box and then heading to the after-match function.
On Saturday they can expect a repeat of Friday night but with a few extra activities planned after the game.
"We've been told to expect to be rubbing shoulders with some pretty important figures on the seventh floor of Hilton Hotel after the game."
And regardless of the final result, Leathem said the main thing is the fantastic experience she is going to have.
"The atmosphere is going to be something else and I'm just so excited."
The other team for the final was still to be determined when Leathem talked to the Chronicle, but she was hoping South Africa had a chance of claiming the 2019 title.
"South Africa's a pretty strong team, they've always been a force to reckon with."
Another Whanganui woman, Brenda Bishop, also won tickets to the final through a different competition. She won a Canon competition when she bought printer cartridges at Warehouse Stationery in Whanganui.
Pete Ellicott, assistant store manager of Whanganui's Warehouse Stationery with Rugby World Cup tickets winner Brenda Bishop. Photo / Supplied
