Panthers playmaker Nathan Cleary will avoid surgery after scans revealed the nature of the ankle injury he suffered in the NSW Blues victory over Queensland on Sunday.

Cleary has been diagnosed with a high grade lateral ankle injury and is currently dealing with a large amount of swelling.

Fortunately the scans showed the syndesmosis in Cleary's right ankle remains intact.

The 21-year-old will be sidelined for up to four weeks, likely ruling him out of the State of Origin decider at ANZ Stadium.

Cleary's immediate replacement in the Panthers side to face New Zealand Warriors will be revealed when coach Ivan Cleary names his squad on Tuesday.