The victory, an extraordinary fifth scalp in a row for the traditional Australian conference battlers, has already made 2014 the most successful season in seven years for the West Australian province. They move to second in the Australian conference behind the Brumbies.

The Force led 13-9 at half-time and scored another two tries in the second half after muzzling the Waratahs' attack.

A try to NSW playmaker Kurtley Beale gave the visitors hope in the 66th minute but without fullback Israel Folau, whom the ARU controversially withdrew from the match less than 24 hours before kick-off, the visitors lacked the class to finish their many opportunities.

The Force also lost fullback Jayden Hayward as a late withdrawal, but managed to pounce on opportunities when they were presented.

NSW put points on the board first with a 45-metre penalty goal from Beale in the ninth minute.

They attacked again, No.7 Michael Hooper making a trademark break, but offloaded into the hands of a chasing Force player. The Waratahs were awarded the penalty and Beale slotted his second attempt, the Waratahs leading 6-0 with 11 minutes gone.

The Waratahs used line speed to shut down the Force attack but ran the gauntlet on the offside rule. Kane Douglas was ruled to be on the wrong side of it in the 16th minute, allowing Force five-eighth Sias Ebersohn an opportunity to put the home side on the board.

Beale missed his next shot at goal but the Waratahs dominated possession, using their big ball carriers Will Skelton, Jacques Potgieter and Benn Robinson to get them into Force territory.

The problems cropped up once they arrived there. Three times in the next 20 minutes the Waratahs conceded a penalty within sniffing distance of the try line.

The only time that didn't happen, it was much, much worse. A pass from Nick Phipps off the base of the ruck to Beale sailed straight into the arms of Cummins.

The Force winger sprinted the length of the field and dived under the posts for the only try of the half. Ebersohn converted to give the Force the lead, 10-6. Both sides added a penalty, with the Force hanging on to a 13-9 lead at the break.

The Waratahs came out firing in the second half but continued to let impatience and small handling errors cruel their momentum.

Returning winger Cam Crawford appeared to have scored in the 46th minute, but referee Angus Gardner ruled obstruction on Crawford's effort, finding fullback Jono Lance had impeded Force halfback Alby Mathewson.

Instead the Force took the points, Mathewson sniping through a gap between Douglas and captain Dave Dennis four minutes later and passing to Cummins for the winger's second try. Ebersohn missed the conversion, the Force leading 18-9 with 30 minutes to go.

Unluckily, the Force lost their three-Test All Black Mathewson in the next few minutes with an apparent shin or ankle injury on his right leg.

But Cummins struck again in the 61st minute, an astonishing belt down the left flank taking everything he had. Crawford and Lance piled in to halt his run but the Test winger could not be stopped.

Beale's effort, converted by Foley, narrowed the gap to nine points with less than 15 minutes to go.

But the Force had a head of steam on and kicked a third penalty goal to put the game beyond reach in the 76th minute.

The Waratahs head back to Sydney on Sunday to prepare for the Bulls.