“I am bowling a lot of deliveries at off stump and on the pads due to my action. It’s only a little change but I have worked hard on it.”
Hazlewood was ably assisted by fellow paceman Pat Cummins, unlucky not to take a wicket on Friday.
“Patty rarely bowls a bad spell to be honest,” Hazlewood said. “He just gets better every time he bowls.”
“We probably wouldn’t have liked to lose a couple of wickets at the end but I think we are only a couple of partnerships away (from avoiding the follow-on),” said left-handed opener Burns after his third score of fifty or more this Ashes.
Rain meant there was no play before lunch.
England resumed on 23-1, with Burns 15 not out and nightwatchman Craig Overton three not out.
Overton had added just two to his score when he edged Hazlewood to Smith at second slip.
Burns, who scored his maiden Test century in the series opener at Edgbaston, cover-drove Mitchell Starc for four and a steered boundary off the left-arm fast bowler, playing his first match of the series, saw him to a 100-ball fifty.
Root should have been out on 54.
But an edge off Cummins went between Australia captain and wicketkeeper Tim Paine — who should have gone for the catch — and David Warner at first slip.
Hazlewood and Cummins kept the pressure on from both ends, each achieving lift and movement in a way that only Stuart Broad had managed when Australia batted.
The Australia duo’s display was a reminder of how much England missed James Anderson after their all-time leading Test wicket-taker, who has been sidelined since the first match with a calf injury, was ruled out of the rest of the series.