Melbourne Storm forward Christian Welch is out for the rest of the NRL season after rupturing the anterior cruciate ligament in his left knee.
Welch, 22, suffered the injury during Storm's 34-22 win over the St George Illawarra Dragons on Sunday.
Scans on Monday confirmed the severity of the injury, ruling him out for the rest of the season.
"We are extremely disappointed for Christian after he had made such a terrific start to the season," Storm football director Frank Ponissi said.
"The club will support him through this recovery and we are certain that with his level of work ethic, he will leave no stone unturned during his rehab.
"We have no doubt that Christian will continue to support the boys throughout the 2017 season and we look forward to seeing him back on the field and playing good footy for Melbourne in 2018 and beyond."
Welch had made eight appearances for the table-topping Storm this season.