Wallabies co-captain Michael Hooper is expected to miss Saturday night's Test against Argentina after picking up an injury at training this week.
Hooper cut a disconsolate figure on Wednesday afternoon as the Wallabies prepared for training at Manly Oval, sources with knowledge of the situation later confirming to ESPN that the veteran flanker had suffered a minor calf injury.
Hooper found sympathy in scrum-half Nic White ahead of training, the duo sharing a quick hug as the rest of the Wallabies' 34-man squad set about finalizing their preparations for the Rugby Championship clash at CommBank Stadium.
While Hooper's injury is understood not to be serious, it is believed he could also be in danger of missing the first Bledisloe Cup Test against the All Blacks in Melbourne on July 29.
A typical recovery from a minor calf strain takes between 1-3 weeks.
Hooper was one of many Wallabies who struggled in last Saturday's 43-12 hammering by the Springboks when Australia had few answers for the South Africans' power game.
Apart from a smart piece of breakdown play that won the Wallabies a penalty, the 31-year-old had little impact on a Test that was out of Australia's reach at halftime.
His calf injury will likely result in either Fraser McReight or Pete Samu earning a start at No. 7 this weekend, the Queenslander potentially the favoured option given his greater on-ball presence.
But there are also widespread concerns that he too might not be big enough to mix it with the elite back-rows in world rugby, including the seemingly ever-expanding Springboks loose forward contingent who did a number on their Wallabies counterparts in Pretoria despite the omission of Kwagga Smith, Jasper Wiese, Franco Mostert and injured skipper Siya Kolisi.
Whatever the case, Hooper is no longer a guaranteed Wallabies selection with coach Eddie Jones having last month announced he was to be a co-captain alongside James Slipper. That decision has left the door ajar for Hooper to be moved to the bench, or even left out of the 23 altogether, in the run to and at the World Cup, something that was almost unthinkable during the Michael Cheika and Dave Rennie Wallabies eras.
Meanwhile, fellow back-rower Tom Hooper is also believed to be a scratching through injury, with the Brumbies youngster suffered a shoulder injury on debut against the Springboks.
The Waratahs' Jed Holloway looms as his most likely replacement given his outstanding debut Test season in 2022, while Rob Leota and Josh Kemeny are likely to come under consideration for a spot on the bench.
Jones will confirm his 23 to face the Pumas on Thursday morning.