The Chiefs continue to lead the standings by a point despite suffering a 28-24 reversal against the Fijian Drua while the Reds were on the end of a 43-19 loss to the Canterbury Crusaders in Christchurch on Sunday.
Max Jorgensen scored a pair of tries to take the Waratahs up to second with a commanding victory in Sydney, the Wallabies winger leading his team to a third win in a row.
"We started to unlock our attack tonight, which was pleasing," said head coach McKellar, whose side have played one game fewer than the Chiefs. "We scored six tries and the backs scored four.
"We had the intent to shift the ball, we managed to do that and at the same time we continued to show that physicality and effort that we've been talking about, and fight. Encouraging. Happy."
The Chiefs remain in pole position even after Drua winger Ponipate Loganimasi scored the game-winning try with 15 minutes remaining at a rain-soaked Churchill Park in Lautoka.
Trailing 12-6 at the interval, the Drua fought back in the second half to pick up their first win of the campaign.
Loganimasi played a key role in the fightback, palming a high-ball into the path of Vuate Karawalevu to score the Drua's second try in the 59th minute after Meli Derenalagi had crossed the line two minutes into the second half.
The former Fiji sevens player then sealed the win with a moment of individual skill, chasing down his own chip over the Chiefs defence before racing onto a second kick as it slithered across the line.
Sevu Reece and Will Jordan each scored a pair of first-half tries on Sunday to ensure the Crusaders ended the Reds' perfect start, the 12-times Super Rugby champions notching up a comfortable win in sunny Christchurch.
Cullen Grace's try gave the home side a sixth minute lead before Reece crossed for his first score 12 minutes later.
Reds winger Filipo Daugunu powered over the line to reduce the deficit, but Reece's second and a pair for Jordan before the interval put the Crusaders in position to take a bonus point win that lifts the New Zealanders to fourth.
Miracle Faiʻilagi led Moana Pasifika to a 40-31 win against the Wellington Hurricanes, the Samoa international scoring a hat-trick of tries in Auckland's North Harbour Stadium to steer Tana Umaga's side to their first success of the season.
"I'm happy for the brothers in the changing rooms," said Moana captain Ardie Savea, who joined the team in the close season, having previously spent ten years with the Hurricanes.
"It's a special feeling when everything can click for the boys."
The ACT Brumbies added to the Auckland Blues' early season woes by handing the defending champions a 21-20 defeat at Eden Park on Friday, the Canberra-based side picking up their first win at the hallowed New Zealand venue since 2013.
Ryan Lonergan slotted over a last-minute penalty to secure the points for the Brumbies, who are now sixth in the table with two wins and two defeats. The Blues, meanwhile, are in 10th.