IT might be the Australian Open, but the water on sale at the nation’s premier sporting event is decidedly unpatriotic.

Tennis fans attending day one of the tournament have taken to social media to express shock that the bottled water on sale is imported from China.

Rather than opt for an Australian brand, organisers are selling Ganten bottled water, which has been shipped from the Chinese city Shenzhen, A Current Affair reports.

Viewers commented on the Open’s use of product placement, with the Ganten logo visible on the side of the tennis umpires’ chairs.

Umpires chairs are also sponsored by Ganten, been asking all day what's Ganten...now I know pic.twitter.com/YhmcEjrMdn — Gavin McKenzie (@gav_mck) January 15, 2018

In a statement, Tennis Australia said the Australian Open was a global event that had “a long history of partnering with international brands”.

The statement pointed out that the Open also partnered with “iconic Australian brands such as Jacobs Creek, Coopers, Vegemite and Country Road”.

“Ganten water is a premium brand that is associated with other major tennis and sporting events, including Juventus FC,” the statement said.

“The Australian Open continues to expand its global reach and partnerships, which helps to grow the sport at all levels in Australia.”