The stroke, even though Root didn't connect, heralded a passage of play that sent Australia from attack to defence in five overs. They started with three slips and a gully but were soon down to a lone catcher. Root didn't put the reverse scoop away, either, sending Scott Boland for a six and a four to deep third. England scored 32 runs in the first three overs of the day and things could quickly have got out of control for Australia.
Cummins provided Australia the first breakthrough with a delivery that will be replayed over and over, much as his ball to Root at Old Trafford in 2019 has been. This time it was to Ollie Pope, an inch-perfect yorker that speared under the bat and knocked back off stump.
The key wicket, however, went to Lyon when he defeated the sublime Root as he came down the pitch, having him stumped for the first time in his Test career after more than 11,000 runs. It was a third stumping of the match for Alex Carey who had waited 16 matches for his first; like with Root, he also effected Virat Kohli's first such dismissal in Tests.
He knew he was going to be attacked by England's batters, so much so that he got his team-mates to try and whack him out of the nets two days before the game began.
"I had Matt Renshaw and Josh Inglis, I just said come and slog me, try and hit me for six every ball," he said.
However, in the second innings, England couldn't score anywhere near the rate against him as the first innings - 3.33 compared to 5.13 on the opening day - which was partly not surprising on a wearing surface but also owed plenty to Lyon's subtleties.
After Root, the dismissal of Harry Brook had him pulling a delivery to midwicket that was not as short as a previous one where a similar stroke had been successful. He also challenged, and kept quiet, Ben Stokes who scored just 15 runs off 35 deliveries Lyon bowled to him while Jonny Bairstow made 4 off 20 balls. It was also another telling overseas contribution in little more than a year, following Lahore (six wickets to seal the series), Galle (nine wickets in a victory) and Indore (11 wickets in a win).
"For me it's about bowling my best ball and trying to get them to defend as much as I can and understanding they don't want to defend," Lyon said. "And that's totally okay. It's a different challenge but it's exciting to be honest. They are playing a positive brand of cricket and I'm bloody proud to be a part of it to be honest."
Lyon's job with the ball in this exhilarating match is now done - and he hopes he won't be needed with the bat on the final day - but England will likely need Moeen to play his part if they are to take victory. Even with a Test on the line, Lyon expressed his understanding for what Moeen is battling.
"Sitting here I have a lot of sympathy for Mo, not coming off any red-ball cricket for two years and thrown into bowling a lot of overs," he said. "The best way I can probably sum it up, and it will probably sound weird, is a singer losing the vocals but expecting to go out and put a concert on.
"It is extremely tough to grip the ball as finger spinners, especially as offies, we put our fingers on the seam and try to spin up the back of the ball, that's where we get spin, drop and drift. So [there's] a lot of sympathy for him, I've been there before, it is quite painful."
The pair can perhaps catch up on the trials and tribulations of offspin after the game is complete on Tuesday. However, who finishes up as the victor and the vanquished, weather permitting at least, remains very much uncertain.
Andrew McGlashan is a deputy editor at ESPNcricinfo