WTC final talking points: Steve Smith's unfortunate final act at Lord's, Cummins wins Starc argument, Lyon's 'defining moment' awaits

At a ground where he's had so much success, you wouldn't expect Steve Smith to be leaving Lord's for the final time in agony.

That appears to be the reality.

It's the major talking point coming from day three at Lord's, along with Australia being on the brink of a shock victory.

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At 36, many expect the home Ashes tour to be Smith's final swansong.

However, his recent form suggests there could be more to come.

Nonetheless, the World Test Championship final is seen as his last hurrah at Lord's.

When he scored 66 in the first innings, it meant became the highest non-English runscorer at Lord's.

It moved him to 591 career runs at the venue, and pushed him ahead of Sir Don Bradman (551), Garry Sobers (571), and fellow Aussie Warren Bardsley (575).

Steve Smith went past the greatest batter ever in becoming the highest non-English run scorer ever at Lord's - known as the home of cricket.

"I love batting here at Lord's," he said after day one.

But now his love affair with the ground appears over and the sight of him with a dislocated finger, dry-heaving and holding back obvious pain will be the final sight.

It's a sad outcome and not how it was meant to be.

But that's cricket, and it doesn't always work out how we want to.

Smith is also poised to miss the upcoming West Indies tour too with the compound dislocation.

The last time he played there was 2015 where he scored 199 at Kingston.

It'll certainly take some interest out of the series but brings intrigue as to who could come in.

Does Sam Konstas open with Marnus Labuschagne and Cameron Green shuffling down? Or does Josh Inglis find his home at No.4?

Cummins shows he's the boss

The sharp eye of Nasser Hussain spotted a slight conflict between Mitchell Starc and Pat Cummins as the struggle for wickets continued.

During Mitchell Starc's eighth over, the first two balls began a trend.

Aiden Markram tried to drive on the up and edged through gully for a boundary. Then he did it again and the ball landed short of mid-off. The third delivery was pushed to point for no run and then Markram drove him down the ground the next. Markram pushed him to square leg for a single with the fifth delivery.

When Bavuma faced up, Starc pulled out of the ball during his stride. He told cover to go back.

During Starc's next over, Hussain spotted a "conversation and a bit of an argument" between Starc and Cummins.

"The captain hadn't given him a man on that drive position, and Starc, maybe concerned about runs, pushed him all the way back," he said.

Then in the ninth over, Usman Khawaja and Cameron Green sat close in the covers.

"It looks like the captain has won that argument, we now want two on the drive," Hussain said.

Cummins deployed two covers. One at short cover and the other regulation.

This was because Cummins dismissed Temba Bavuma in the first innings with a brilliant catch from Marnus Labuschange in the covers.

Can Lyon step up?

It's been a while since Australia has needed the heroics of Nathan Lyon on the final day of the Test.

But now the platform is there for Australia's off-spinner.

Lyon was barely used during the home series against India, such was the might of the pace artillery.

Then in Sri Lanka he and Matt Kuhnemann worked brilliantly together to put Sri Lanka in a spin.

However, no situation there was similar to what's set up on day four at Lord's.

Despite his age, Lyon has shown no indications he's ready to step away and the World Test Championship final will be the perfect situation to showcase why he's still world class.

This could be his defining moment.