The England captain may also be wondering what else is on Smith's bucket list after Australia won the fourth test by 185 runs Sunday to take a 2-1 series lead which ensures it retains the Ashes.

"I've been here a few times when things haven't quite gone our way or we haven't performed to the best of our ability," Smith said in a post-match TV interview at Old Trafford. "To come back and get the urn here was always one to tick off my bucket list."

Smith has scored 144, 142, 92, 211 and 82 in his five innings in the series so far. He missed one innings in the second test and the entire third test — which England won by one wicket — because of a concussion.

The 30-year-old Smith has been the single biggest difference between the two teams throughout the series.

Returning to test action following a 12-month ban for his role in a ball-tampering scandal in South Africa in March, 2018, Smith has — so far — scored 671 runs in this Ashes series at an average of 134.20. It has lifted his career test average to 64.81 and has been the kind of performance that has drawn comparisons with Don Bradman, who was widely regarded as cricket's greatest batsman.

Smith was the No. 1-ranked batter in test cricket before he was suspended last year by Cricket Australia. He regained the top ranking from India captain Virat Kohli last week.

Tim Paine, who replaced Smith as Australia's test captain last year, on Sunday described the No. 4 batsman as the "best player I have ever seen."

And Paine had a warning which Root's England is likely to take seriously ahead ahead of the fifth test in cricket's oldest regular international series.

Smith "is just a genius and I never had any doubt he would come back and be the player he was," Paine said. "The scary thing is he's getting better."