Vatuvei left the Warriors in July to sign with the English club Salford. He has scored five tries in eight appearances with the Red Devils.
Salford have released a statement saying Vatuvei had suffered a suspected serious Achilles injury.
The 31-year-old wing is awaiting the results of a scan to determine the severity of the injury, which he suffered in training on Friday.
"It's terribly unfortunate that Manu has sustained an injury this close to the start of the season," said Salford head coach Ian Watson.