Having taken the scalps of both England openers yesterday, McGrath opened his Day 3 account when the dangerous Kevin Pietersen was adjudged LBW after being struck on the back pad after not offering a shot.
Brett Lee then claimed his only wicket of the innings, but it was a crucial one at that, as he had England captain Andrew Flintoff caught behind for a duck.
Ian Bell tried his best to hold things together for England as his teammates fell around him like umpire Billy Bowden did when he was struck by a hefty Bell sweep shot while officiating at square leg.
Bell faced 162 balls for his 50, displaying the patience and poise that some of his fellow batsmen needed to show during their time at the crease, before Ponting took a sharp catch to dismiss him off the bowling of Stuart Clark.
Clark and McGrath then combined to wrap up the England tail with the latter adding the wickets of Geraint Jones (19), Stephen Harmison (0), and Ashley Giles (24), to put egg all over the faces of his pre-match detractors.
Bowling in his first Test appearance in Australia, Clark was almost as impressive as his New South Wales teammate, finishing with the excellent figures of 3 for 21 off 14 overs.
Aussies choose to bat again
Amazingly, Ponting chose not to enforce the follow-on even with a 445 run lead, instead asking his openers to put on some quick runs and the England bowlers to labour under the afternoon sun.
Justin Langer and Matthew Hayden then made batting look easy on a pitch that just hours earlier looked like a minefield when the Englishmen were at the crease.
Hayden was eyeing off a big total of his own, scoring 37 off 41 balls, before foolishly running himself out when attempting a needless second run on the arm of James Anderson coming in from fine leg.
Langer finished the day on 88 not out to add to his well made 82 in the first innings, while Ponting racked up another half century, ending on 51 not out and in doing so passed the milestone of 9,000 Test runs in his 177th innings.
By the end of the day, Australia had piled on a further 181 runs, far surpassing England's first innings total in little over one session of play.
The Australians may either declare overnight or bat on for a few overs on Day 4, but it will not be long before McGrath, Lee, Clark and Shane Warne are back with the ball looking to finish the match off.