Australia lock Will Skelton is returning to France to rejoin club La Rochelle before the start of the Top 14 season, in a blow for the Wallabies' Rugby Championship hopes, Rugby Australia confirmed on Tuesday.
Skelton will miss home tests against Argentina in Townsville and Sydney, with no guarantee he will return for the final matches against New Zealand.
Australia are second on the Rugby Championship table behind the All Blacks following a win and a loss to the third-placed Springboks in South Africa.
Skelton missed a one-off test against Fiji and the British and Irish Lions series-opener with a calf injury in July, but has been an important player for the Wallabies since returning for the second Lions test in Melbourne.
While Skelton's departure opens the door for reserve lock Lukhan Salakai-Loto, it leaves Joe Schmidt's squad further stretched amid a rash of injuries.
Prop Allan Alaalatoa is nursing a shoulder injury and unlikely to be named in Schmidt's squad for the home tests against Argentina on Thursday.
No 8 and captain Harry Wilson, prop Taniela Tupou and hookers Matt Faessler and Lachlan Lonergan are also injury doubts for the Pumas series which starts in Townsville on 7 September.