SA declare early v NSW after Lehmann hits Shield ton

Jake Lehmann was 101no as SA declared on 7-309 on day three against NSW in the Sheffield Shield. (Matt Turner/AAP PHOTOS) (AAP)

A daring declaration from South Australia captain Jake Lehmann has set up the possibility of a result in the Sheffield Shield match against NSW in Adelaide.

South Australia declared late during the middle session on day three at 7d-309 as the home side conceded a 138-run deficit in the final-round fixture.

At tea, NSW were 0-26 in response.

The visitors had posted 9-447 when they declared midway through day two on a Karen Rolton Oval pitch that is offering little assistance to the bowlers.

Chris Tremain has taken two wickets as bat still dominates ball in NSW's Shield match in Adelaide. (Dan Himbrechts/AAP PHOTOS) (AAP)

Lehmann led the way for the fourth-placed Redbacks with the bat, posting 101 not out in a 178-ball innings that featured 13 boundaries.

Daniel Drew was the other main contributor for the home side with a more watchful 85.

Chris Tremain and Ryan Hadley both picked up 3-75 for the Blues.

Bottom-side NSW are chasing their first win of the season.