Israel Folau was injured on his Test return as Tonga lost 36-0 to Fiji in the Pacific Nations Cup.
The 33-year-old, a fundamentalist Christian, won 73 caps for Australia but had his contract terminated in 2019 after posting a homophobic tweet.
A change in World Rugby's rules last year allowed him to switch allegiance to Tonga.
Folau injured his leg in a collision when chasing a kick and limped off in the 27th minute against Fiji.
He was listed as 'Isileli Folau' by Tonga and named on the right wing for the match in Suva.
He had only two ineffectual touches before being replaced and it is unclear if he will be fit for Tonga's remaining games in the four-nation tournament.
In the earlier game, Samoa secured a dramatic 31-26 win over Australia A.