Momentum is a curious, intangible beast, impossible to measure but easy to see. There are players who claim that it doesn't exist, yet what else but momentum can explain the fact that England are even remotely back in this Test match? England, who were thrashed by 10 wickets in Brisbane. England, who here sent Australia in, saw them bat into six sessions and declare at 8 for 442. England, who batted so poorly that they gave Australia the chance to enforce the follow-on.
And therein lies the crux of this momentum shift. Steven Smith did not make England bat again, preferring to give his bowlers a rest. In doing so, he made his own men bat under lights on the third evening, when England's bowlers hooped the ball around and gained confidence. On the fourth day, Australia were knocked over for 138, and James Anderson claimed the first five-wicket haul he had ever managed in 15 Tests in Australia. The previously anosmic England had the trace of a sniff.
By stumps, England had doggedly worked their way to 4 for 176, with their captain Joe Root the key man, unbeaten on 67, alongside Chris Woakes on 5. The momentum had threatened to swing back to Australia late in the evening when Pat Cummins rattled the top of Dawid Malan's off stump, and might have done so had Woakes not jammed down on a sizzling Cummins yorker from the penultimate ball of the day.
In the end, England went to stumps needing a further 178 runs with six wickets in hand. Yet if Australia's position was much the stronger, England might have felt that they won the day, for they ended it with more chance of victory than when they had started. In the final session it was the Australians who looked nervy, Smith losing both of his side's reviews in the space of three balls as he sought a fourth wicket.
Objectively, this made little sense. To win, England would need to rewrite history. Never before have England chased down a target as high as the 354 they were set here. For nearly 90 years, their record chase has been 332, achieved by a team that boasted Jack Hobbs, Herbert Sutcliffe and Wally Hammond in their top four.