This Wednesday morning, the Pallaskenry 27-year-old and colleagues finished sixth in their semi-final on the Chaobi river at Shunyi Olympic Rowing Park.
The result puts Ireland into the B final, which takes this Thursday morning between 10.45-11.00am - RTE One television will provide live coverage.
In the B final O'Neill's Irish crew will face opposition from Belarus, USA, New Zealand, Netherlands and Italy as the final placings from 7-12 are confirmed.
The St. Michael's Rowing Club member and colleagues; Jonno Devlin and Sean Casey and Cormac Folan found themselves in the faster of the two semi finals this Wednesday morning.
Ireland's semi-final was won by Great Britain with Australia and France also reaching Saturday's final.
Joining them from the second semi-final are Slovenia, Czech Republic and Germany.
In the extreme heat of the Chinese afternoon the Irish time for the 2000metres course was five minutes and 58.14 seconds - less then four seconds behind the winners. In fact Ireland's time was four seconds faster than the time the crew posted in Saturday's heat.
In lane five Ireland were slow from the pontoon and were last at the half way mark.
In the second half of the race, Ireland briefly edged towards fourth place, ahead of the USA, but there was no grandstand finish from the Limerickman and his crew.
The semi-final saw Ireland renew acquaintances with Australia and France.
Last Saturday, the Irish crew had defied the odds to finish ahead of France and advance directly to the semi finals - thus avoiding the backdoor route of the repechage.
In their heat, Ireland were grouped with Australia, German and France and most observers felt that Ireland would have to take the backdoor route. France made the early move, with Australia gaining ground, and after the first 500m the Irishmen were in fourth place with just over a length covering all four crews.
The positions were unchanged at half-way when Ireland made a strong push and were fastest in the third quarter.
They briefly held on to second place as France began to pay the price for their early pace, but then the Germans mounted an assault within the closing stages to deny Ireland, second place, but qualification was secured.