Root is the visitors' best batsman but has been kept relatively quiet in the first two games of the five-match series.
The England skipper has only scored two half-centuries in four
innings as his lack of a big score has contributed to his side being
two-nil down with three matches still to play.
Root's wicket has twice been taken by Hazlewood and Pat Cummins with
Hazlewood saying the bowlers are more focused when the visiting captain
walks to the crease.
Hazlewood told reporters in Perth on Tuesday: "All the bowlers want
that wicket and there's obviously a couple of key ones which we've
"Joe is the key, he can hold the innings together and score runs
pretty freely when he gets some poor bowling his way, so everyone has to
be ready when he comes in and stop that quick 20 or 30 runs early.
"It's obviously a little bit more important, the time of that start
of that fifth day when things could have gone either way, so you're a
bit more focused, (there's) not as much room for error against those
"Got to be on your game from ball one and he's obviously going to
punish anything that's not your best ball. Still the key to him is
bowling your best ball more often than not and hopefully keep the runs
to a minimum and keep taking his wicket.
"I think I'm just getting better as time goes on. Probably just my
length I think, my length especially on the last day, so obviously be
continuing to work on that and I think it's on the rise so hopefully
keep getting better."
The right-arm seamer has also praised the work done by off-spinner
Nathan Lyon in the series so far as it has allowed the Australia pacers
to manage their workloads.
Lyon has arguably been the best bowler on show, from both sides, in
the series and Hazlewood feels their three pacemen (himself, Cummins and
Mitchell Starc) can play in all five Ashes Tests.
The 26-year-old added: "I've only bowled under 40 overs in both games
so I feel pretty fresh at this time of the year and the other quicks
are pretty similar.
"They have probably bowled more than me but the way Nathan has bowled
has given us the opportunity to sit out one or two spells here or there
and him just go from one end.
"He's been bowling beautifully and taking wickets as well as keeping runs to a minimum, still feels pretty fresh at the moment.
"I think (I can get through five Tests), it's still a long way off
obviously and just got to take it game by game as a fast bowler or spell
by spell at some stages, but feel as good as I have."