One of Australia's most consistent performers throughout 2025, McDermott was assisted from the field at Auckland's Eden Park midway through the first half on Saturday after getting caught awkwardly in a ruck.
Scans revealed the worst possible news with the 27-year-old requiring an operation that will end his year and with a recovery time of around six months, will likely put a dent in the Queensland co-captain's participation in Super Rugby Pacific's opening rounds.
"Scans have confirmed Tate McDermott will require surgery on a hamstring injury he suffered in Auckland," the Wallabies said in a statement on social media.
"He is expected to spend an extended period of time on the sideline throughout his recovery."
Wallabies coach Joe Schmidt had already called veteran Nic White into the squad as a training partner ahead of Saturday's second Bledisloe Cup Test in Perth as the Australians look to respond to a 33-24 defeat.
It's the second time White has come out retirement and answered Schmidt's call to play on, with the coach describing him as the "gift that keeps on giving".
McDermott had been coming off the bench for the Wallabies, key to second-half resurgences which had seen them secure victories over South Africa and Argentina.
A former sevens player, he showed his versatility during the British & Irish Lions series and against the Springboks when he was came on as a winger due to injuries.
Finally in the run-on side in Auckland, which was his 50th Test, McDermott only lasted 18 minutes before he was replaced by Ryan Lonergan in his Test debut.
Jake Gordon, who himself has battled hamstring issues, is expected to be fit for the Optus Stadium clash with will vie with Lonergan to start, with White able to slot in should either player go down.
Following the second Bledisloe, which doubles as the final round of the Rugby Championship, the Wallabies have a few weeks off.
Their next Test is against Eddie Jones's Japan on October 25 in Tokyo en route to their northern hemisphere spring tour with Tests scheduled against England, Italy, Ireland and France.
8°C