Ben Smith was frustrated with the manner in which Highlanders opened the door for a Waratahs fightback after the Super Rugby champions clung on for a 30-26 victory.
Friday's contest at Allianz Stadium appeared to be over at half-time when the visitors stormed into a 22-0 lead against the 2014 champions, who were left to rue two missed penalties and a knock-on from Kurtley Beale close to the try line.
Elliot Dixon's second try and a drop-goal from Lima Sopoaga put them 30-0 up, but debutant Jed Holloway helped himself to a hat-trick after coming on at half-time as Waratahs roared back.
Highlanders held on to seal a third win in their first four matches, but co-captain Smith knows the second-half showing was not good enough.
He said: "The Waratahs played well in that second half and put a lot of pressure on us. Defensively we didn't stay in it, we let them back in the game. I'm just disappointed with the way we played that second half. We just didn't work hard enough for each other but at least we got the win."
Joe Pietersen missed a last-gasp penalty to prevent Sharks from making it four wins from four as they drew 16-16 at Bulls, while Hurricanes thrashed Western Force 41-6 in Palmerston North.
Hurricanes 41-6 Western Force
Force were very much in it when Peter Grant's second penalty of the match early in the second half reduced the deficit to 10-6, but they were steamrollered as the rampant Hurricanes ran in five second-half tries to add to a first-half score from fit-again captain Dane Coles.
Waratahs 26-30 Highlanders
There appeared to be no way back for the 2014 champions when they went in at half-time trailing 22-0, with Ryan Tongia, Liam Squire and Elliot Dixon scoring tries. However, it was a very different story in the second half and Holloway's debut treble raised hopes of a remarkable fightback, but the home side ran out of time.
Bulls 16-16 Sharks
Bulls led 13-6 at the break after Warrick Gelant scored the solitary try of the first half, but Willie le Roux's converted try levelled the match. Tian Schoeman's penalty with time almost up made it 16 apiece, then Joe Pietersen missed the chance to win it from the tee at the death.
THE KEY MOMENTS
It could have been a different outcome had Waratahs not been so sloppy in the first half, with Beale's spill proving costly when a try was there for the taking and the Australia international also missing two penalties before the break.
Force were well in the game at 10-6 down, but they fell apart after Justin Marshall scored Hurricanes' second try with just over 20 minutes to play, while Pietersen's failure from the tee right at the end denied Sharks a dramatic win.
Waratahs captain Michael Hooper: "We showed what we can do but it's not how we want to start games. We didn't read the game well enough, our direction was way off. In the second half we started to get that flow, the calls were good and the forwards were carrying hard and that got us into the game.
"We couldn't go any further behind so we just started playing. We've got to change our mentality at the start of the game and we'll be a very dangerous outfit."
Hurricanes skipper Coles: "We had to grind away. In the second half we kept our intensity up, We knew if we did that we could open the game up like we did."