Tom Walsh will compete for another Olympic shot-put medal on Thursday in Tokyo – but only just – after a truly bizarre night in the Japanese capital.

Rated as one of the top contenders, Walsh was headed for a shock exit at the qualification phase, after fouling his third and final attempt.

At that stage Timaru's favourite son had missed the cut for the final, which would have been one of the biggest shocks in New Zealand Games history, given the 29-year-old's pedigree in the event.

The Rio bronze medallist had challenged the officials' decision – which looked extremely marginal – but to seemingly no avail.

After a lengthy review involving a team of umpire and judges, Walsh's attempt of 21.49m was judged legal, sending him from eighth – and going home – to the top qualifier in group A.

More drama was to follow, however, as the decision to overturn was itself overruled - before officials again decided to allow Walsh's attempt.

It was unexpected drama, and only time will tell how it affects the 2019 World Championship bronze medallist in the rest of the competition.

Walsh walked out of the stadium at 11.15pm (NZT), waving goodbye to the television cameras, but still unsure of his fate, before the decision was confirmed a few minutes later.

Tom Walsh qualified for the final of the men's shot put - after farcical scenes on Tuesday night. (Photo / Getty Images)

On a night where many of the big guns in group A struggled, Walsh's plight seemed to catch the attention of the rest of the field.

After fouling on his first attempt, Walsh also drew the red flag on his second throw, before it was judged legal after a lengthy review, but nowhere near long enough to make the cut - at 20.38m.

Walsh still needed to find a big final effort, which he did, eventually.

In a positive sign, the Rio Bronze medallist looked outwardly comfortable in his first outing at these Games, despite the drama.

While some of his competitors seemed to miss the presence of a crowd – and the associated atmosphere that shot put exponents love to feed off – Walsh was unfazed.

He offered his usual mark of relaxation, happily waving to the television cameras between attempts and periods of intense focus.

On a humid night in Tokyo, Walsh looked to have gone close to the qualification mark of 21.20m on his first attempt, propelling the shot high into sky, but drew a marginal red flag.

His second attempt was delayed by a medal ceremony across the other side of the track, before again appearing to go slightly wrong.

It didn't go as far as the first attempt and was called foul as Walsh's foot clipped a microphone near the front of the circle.

But the official's decision was reviewed, before being judged as legal, before the farcical scenes after his third attempt.

A bemused Walsh could be seen questioning the officials and told Sky Sport he wasn't sure what was going on at first.

"I wasn't sure why the guy was calling me," Walsh said.

"I thought my first throw was fine but he fouled me. The second I got a bit tight and pushy and when he called me again I was like, 'hold on'.

"The third one he fouled me again and this time I said, 'what's going on here?'.

"I finally managed to get that overturned, too. It's not the way I would have liked to do it [qualify for the final] but it had to be done."

Tom Walsh speaks with judge Trevor Spittle during the men's shot put qualification. (Photo / Getty Images)

Asked if he thought he was heading for a shock early exit, Walsh joked that he was "always in total control".

"That took a few years off my life. Before I got here tonight I was gonna die at 85… after that I'm gonna die at 80."

Brazil's Darlan Romani (21.31m) and Egypt's Mostafa Amr Hassan (21.23m) were the only other competitors to achieve the automatic qualification mark.

Serbia's Armin Sinancevic (20.96), 2016 silver medallist Joe Kovacs (20.93m) and fellow American Payton Otterdahl (20.90m) were the next best among Group A.

Joining Walsh in the final is compatriot Jacko Gill, who qualified from Group B with a best effort of 20.96m.

Gill finished sixth in his group, won by American Ryan Crouser who managed a massive 22.05m and will be Walsh's toughest competition for gold.

* Earlier Julia Ratcliffe managed a respectable ninth in the women's hammer final.

The 29-year started confidently – but couldn't build on it – to just miss out on the cut for the second phase of the final eight by a margin of 18cm.

She managed attempts of 72.61m, 72.69m, and 71.79m, solid throws but all shy of her personal best of 73.55m.

Julia Ratcliffe finished ninth in the hammer throw. (Photo / Getty Images)

Ratcliffe also couldn't replicate her best effort of the heat, where she recorded 73.20m but she will still reflect on her Olympics debut with some pride, as the Hamilton product finished ahead of notable Americans Brooke Andersen and Gwen Berry, who were seen as medal prospects but struggled with the pressure of the decider.