Smith survived a run out chance despite being out of his ground.
It all happened during the 78th over of Australia’s innings when Smith nudged a delivery from Chris Woakes towards mid-on and scampered for runs, giving Pat Cummins a call of two.
However, by the time Smith turned for the second run, substitute fielder George Ealham swooped down the ball, picked it in one swift motion, and hurled them at the stumps, where Jonny Bairstow was ready to pouch and dislodge the bails.
At first, it appeared that Smith was well short of his crease. However, after watching the replays from different angles, TV umpire Nitin Menon came to a conclusion that Bairstow knocked off a bail with his arm before the ball reached him and by the time other bail was removed, Smith was in his crease.
After the day’s play, veteran England pacer Stuart Broad said umpire Kumar Dharmasena told him that Smith would have been given out if zing bails had been in use.
"I honestly don't know the rules, I think there was enough grey area to give that not out. It looked like benefit of the doubt sort of stuff, first angle I saw I thought out, and then the side angle it looked like the bails probably dislodged," Broad said as quoted by ESPNcricinfo.
"Kumar said to me if it was zing bails it would been given out, I don't really understand the reasoning why," he added.
Under the Laws, the bail has to be completely removed. Law 29.1 states: "The wicket is broken when at least one bail is completely removed from the top of the stumps, or one or more stumps is removed from the ground."
In fact, Steve Smith had started walking back to the pavillion as he thought that he was outside the crease.
"I saw the initial replay and saw the bail come up, and when I looked at it the second time looked like Jonny might have knocked the bail before the ball had come," Smith said in a press conference after the close of play on Day 2.
"Looked pretty close at that stage, if the ball had hit at the initial stage when the bail came then think I was well out of my ground."
"I know now that he's very quick, the next one we hit out there when it was a similar push for two, I was like, gee, this guy's tearing around the boundary, he's coming at pace. Had I known that previously I might have just stayed there for the single," he remarked.
With luck on his side, Smith went on to score 71 and helped the visitors take a first innings lead of 12 runs.
"Did I pull the trigger too early? Maybe. But had I not got out, Murph might not have come in and smacked 30 like he did. We are in the position we are because of our batters, you can't fault what the bottom few did. Thought the partnerships they put together were outstanding."
"A lot of us got starts, the scorecards are very similar in a way, and we weren't able to capatalise and [turn] one of those partnerships that were 40-50 into 100-150 and that gives us a decent lead. Bit disappointed from that aspect," the Australian batter added.
(With ANI Inputs)