But the tenacious left back is on a mission for a third in as many games against Sydney FC this season to catapult the defending champions back into the W-League grand final.

After finding the back of the net just once in her first 76 games during the past seven years, Begg has tripled her career tally with goals in both of this season's fixtures against the Sky Blues.

It's a source of much amusement for the 24-year-old defender, who would love to continue her rare goal-scoring form in Sunday's semi-final at McKellar Park.

"I never say no," Begg said.

"I definitely look forward to getting out there and give it my best shot.

"It's always nice to contribute that way."

Begg's goal in Canberra's 3-0 win at home against the Sky Blues in round two was her first in almost four years.

But she didn't have to wait anywhere near as long to get back on the scoresheet, pushing forward to fire the winner with the clock winding down for a 1-0 victory in the return clash in Sydney.

That put Begg in an unusual situation – challenging twin sister Ashleigh Sykes for the highest goal-scorer in the family.

Since then, Sykes has turned on the afterburners to fire home seven goals to show why she's one of the most dangerous strikers in the W-League.

"She was a bit annoyed at the start of the year because we were level on goals at the start of the year and she was like, that's a bit embarrassing, but it's all good now," Begg laughed.

"Ash started her goal-scoring career scoring solely against Perth and so I'm hoping if I continue scoring just against Sydney then I'll score goals like Ash is right now."

The next tall tale is how Begg's pleas with United coach Rae Dower to play up the field go unanswered.

Goals are always a welcome bonus, but Begg's true value to United is as a key cog of a water-tight defence.

United has conceded just eight goals from 12 games this season, with four of those coming in one game against the juggernaut that is Melbourne City.

United's record is more imposing at McKellar Park, having not been breached in more than a year in a span of more than 600 minutes.

"We've started to get some really good gelling between the back four," Begg said.

"At the start it was a bit rusty, we were leaking goals left, right and centre.

"But once we got that sorted out with Lydia (Matildas goalkeeper Lydia Williams) behind us, we've settled down a lot."

Williams has been rewarded for her impressive form with a contract with US National Women's Soccer League side Houston Dash, the same club which featured Canberra defender Ellie Brush.

W-League semi-final: Sunday: Canberra United v Sydney FC at McKellar Park, 2pm. Tickets available from the gate.