The Waratahs made it back-to-back victories in Super Rugby as they edged the Force 23-19 at Allianz Stadium in Sydney on Sunday.
A try from Adam Ashley-Cooper, making his 100th competition appearance, and the boot of scrum-half Brendan McKibbin saw the 'Tahs prevail.
In reply, Alfie Mafi crossed for the Force while Sias Ebersohn added fourteen points off the kicking tee in a result that could have gone either way.
The contest was disrupted by both teams being heavily penalised at the breakdown, which led to a busy game for kickers McKibbin and Ebersohn.
"It was tough, we made it hard on ourselves," Waratahs captain Dave Dennis said afterwards.
"We didn't perform how we wanted in some areas. There wasn't a lot between us ... but we have got the points and it worked out well."
Western Force spent a total of seven and a half minutes in the Waratahs' final quarter during the match but only had a 54th-minute try from full-back Mafi to show for their superior statistics.
The Force, who got within four points of the Waratahs with 20 minutes left, could not breach the home defence despite their weight of possession and have now won just one out of six.
"When we play we're a good rugby side, but we're just not playing for the entire 80 minutes," Force skipper Matt Hodgson said.
"We're trying to work on our combinations. We're a new side, we have a whole new backline so we are trying to integrate the forwards and backs together.
"We're showing in patches that we can do that, we just can't do it all the time."
The Waratahs face a big test against the Hurricanes in Wellington next Saturday, while the Force are at home to the Rebels, who are returning home from two losses in South Africa.
Pen: McKibbin 6
Pen: Ebersohn 4
Waratahs: 15 Israel Folau, 14 Peter Betham, 13 Adam Ashley-Cooper, 12 Rob Horne, 11 Drew Mitchell, 10 Bernard Foley, 9 Brendan McKibbin, 8 Pat McCutcheon, 7 Michael Hooper, 6 Dave Dennis (capt), 5 Kane Douglas, 4 Sitaleki Timani, 3 Paddy Ryan, 2 John Ulugia, 1 Benn Robinson.
Replacements: 16 Tatafu Polota-Nau, 17 Sekope Kepu, 18 Mitchell Chapman, 19 Jed Holloway, 20 Matt Lucas, 21 Ben Volavola, 22 Tom Kingston.
Western Force: 15 Alfie Mafi, 14 Patrick Dellit, 13 Winston Stanley, 12 Kyle Godwin, 11 Junior Rasolea, 10 Sias Ebersohn, 9 Alby Mathewson, 8 Richard Brown, 7 Matt Hodgson (c), 6 Ben McCalman, 5 Hugh McMeniman, 4 Toby Lynn, 3 Salesi Ma'afu, 2 Heath Tessmann, 1 Pek Cowan.
Replacements: 16 Ben Whittaker, 17 Kieran Longbottom, 18 Sam Wykes, 19 Chris Alcock, 20 Chris Eaton, 21 Sam Christie, 22 Sam Norton-Knight.
Referee: Steve Walsh (Australia)
Assistant referees: Andrew Lees (Australia), James Leckie (Australia)
TMO: Peter Marshall (Australia)