Hall was hurt in last Saturday’s 48-22 win over Toulouse Olympique and scans on Monday revealed damage to an anterior cruciate ligament (acl).
The injury means he will be sidelined for around eight months. Hall will begin a two-year contract with Australian NRL club Sydney Roosters when his Rhinos deal expires at the end of this season.
Rhinos director of rugby Kevin Sinfield described the scan results as “desperately disappointing news for Ryan first and foremost”.
He said: “He has been a big player for the squad this season and I know how much he wanted to help the side during our Qualifiers campaign to make sure he finished his time at the club on the best possible note.”
Sinfield is confident the injury will not derail Hall’s NRL career, adding: “He is a complete professional who looks after himself and I am sure he will fully recover from this setback.
“Our medical team will be in touch with the Roosters to ensure Ryan has the best possible support to get back to playing as soon as possible.
“In the meantime, Ryan knows he has the backing of everyone here at the Rhinos.”
Hall, 30, made his Rhinos debut in 2007 and scored 233 tries in 330 games for Leeds. He is fifth in the club’s all-time list of try scorers, behind club legends Eric Harris, John Atkinson, Alan Smith and Danny McGuire.
A six-time Grand Final winner, he scored tries in the 2008, 2011 and 2012 Old Trafford title deciders and collected the Lance Todd man of the match trophy after crossing twice in Leeds’ 2014 Challenge Cup final triumph.
Other career highlights include a long-range interception in the 2012 World Club Challenge against Manly Sea Eagles and the last-gasp try at Huddersfield which sealed the 2015 league leaders’ shield.
Hall, who has scored 35 tries in 38 Test appearance, will miss England’s series against New Zealand this autumn.
Meanwhile, Rhinos will be without on-loan prop Dom Crosby for the next two games. He was handed a one-match penalty by the Rugby Football League’s match review panel for a grade b high tackle and a similar punishment for use of his forearm/elbow in the game against Toulouse.
He could appeal, but would risk the bans being increased.
The two game ban will keep him out of Sunday’s trip to London Broncos in the Betfred Qualifiers, plus the visit of Hull KR on Saturday, September 1. The review panel issued cautions to Rhinos’ Richie Myler (tripping) and Anthony Mullally (raising knees in tackle).