The NSW Waratahs have resisted a spirited challenge from the Western Force to remain unbeaten in 20 Super W matches since the competition's start in 2018.

The NSW Waratahs have survived a surprise scare to preserve their incredible four-year unbeaten record in Super W rugby.

The four-time champions needed two late tries to see off the Western Force 31-14 at Leichhardt Oval on Sunday.

The match was tied up at 14-14 until the 63rd minute when Georgina Tuipulotu dived over in the right corner to break the deadlock.

Prop Bridie O'Gorman then secured the victory with an unlikely but memorable 30-metre runaway try after following through a chip kick from a Waratahs lineout win.

"That is the best try I have ever seen," said Waratahs captain Katrina Barker.

"But that's all heart. She chased the kick, she was the only one there and that's all heart."

The Waratahs remain undefeated in 20 matches since the Super W's establishment in 2018.

But the latest victory didn't come easily, with the Force putting up more than a fight for the opening hour and a bit.

"Definitely proud of the girls. We stayed in it," said Force skipper Trilleen Pomare.

"We were in it that whole 80. I think it just fell away from us that last 10.

"Disappointed at losing - we're not here to just have snakes and halftime oranges - but proud of the girls."