Injury-ravaged Daniel Worrall's Ashes hopes have been rocked as NSW built a healthy lead on day three of their JLT Sheffield Shield clash with South Australia at the SCG.

With Worrall out of the Redbacks' attack because of a back injury, the Blues took the game by the scruff of the neck on Sunday before declaring at 8-541.

At stumps, the Redbacks were 0-18, still needing 143 runs to make NSW bat again.

Openers Jake Weatherald (5 not out) and Conor McInerney (11 not out) will resume at the crease on Monday.

Blues openers Daniel Hughes and Nick Larkin both made tons while Moises Henriques fell agonisingly short of triple figures as NSW took control of the game on Sunday.

Blues allrounder Henriques was caught and bowled by part-timer McInerney for 99 on the stroke of tea trying to dance down the pitch and bring up his ton.

The home side lost Hughes (134) and Larkin (109) in the opening session, however that didn't halt their progress as they passed South Australia's first-innings total of 380 after lunch.

Skipper Peter Nevill (57) and Jason Sangha (37) made handy contributions as the Blues put their foot down late in the day before declaring.

Worrall did not bowl during the Blues' innings on day three after suffering a recurrence of a back problem, however it isn't clear how serious the injury is.

After missing five months earlier in the year, it shapes as a big blow to his chances of being on the plane to England next year.

Worrall was forced to return home early from an English county stint in June because of a fractured foot, before missing South Australia's one-day cup campaign and their opening three Shield matches because of back soreness.

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Worrall rises from winter of discontent
He made a spectacular return last month, taking 10 wickets against Western Australia before claiming seven scalps against Tasmania.

Known to be well-liked by Australian selectors, he would have been considered for a spot in the expanded Australian squad for the Adelaide Test had he been able to get more cricket under his belt earlier in the season.

NSW XI: Peter Nevill (c/wk), Daniel Hughes, Nick Larkin, Kurtis Patterson, Moises Henriques, Jason Sangha, Jack Edwards, Stephen O'Keefe, Sean Abbott, Harry Conway, Greg West.

South Australia XI: Jake Lehmann (c), Jake Weatherald, Conor McInerney, Kelvin Smith, Callum Ferguson, Tom Cooper, Alex Carey, Nick Winter, Adam Zampa, Joe Mennie, Daniel Worrall.