It is the first day of the Otago athletics championships and it will give a good indication of prospects for the New Zealand championships in Auckland next month.
O'Shea (23), an accountancy student, has his eyes on the Otago record of 50.48sec that Roger Johnson (Ariki) set at the Munich Olympic Games in 1972.
It will be O'Shea's first 400m hurdles race since he ran his personal best time of 51.62sec at the Melbourne Classic two years ago.
His 400m flat time of 47.35sec at the Caledonian Ground last Saturday indicates O'Shea is in the right condition to break the hurdles record.
''I'm excited about the prospect,'' he said.
''But it will be tough getting used to the hurdles again. I hope to recapture the rhythm I need over the next six months.''
Injuries have kept O'Shea away from the hurdles over the last two years and he knows it will not be easy getting back into the event.
He has been pleased with his training on the hurdles under the direction of coach Brent Ward.
''I am training well. I just have to grow back into the hurdles again.''
O'Shea's goal this season is to qualify for the World University Games in Russia in the 400m hurdles and the flat 400m.
He will be part of the New Zealand University 4x400m relay team that will compete in Europe from May to get a qualifying time.
He is confident of breaking the New Zealand hurdles record of 49.90sec that Nic O'Brien (Counties-Manukau) ran in the United States in 2003.
The 400m hurdles will be the feature race of the Otago championships today.
O'Shea will also be involved in the big race of the championships on the second day next Saturday when he faces clubmate Andrew Whyte in the senior men's 400m.
Whyte (19) broke the six-year-old Otago 400m record that Cory Innes (Taieri) ran in 2006 in Europe last winter. His time was 46.42sec.
Whyte, the New Zealand junior champion last season, has been injured since his return to New Zealand and will be having his first race.
O'Shea would like to take the Otago record off Whyte. He knows it will not be easy but his confidence is buoyed after running the fastest 400m time in the country this season at the Caledonian Ground last Saturday.
O'Shea has been in top form this year and demonstrated this when he won the Time Buster around the Octagon last month.
He is a member of the New Zealand High Performance Academy and knew what to do after hammering his legs in the Time Buster. He had a session on the foam roller at the Academy gymnasium soon after his race.
''I knew exactly what I had to do when I finished that race,'' O'Shea said. ''It is like a self-massage.''
The other key sprint event today is the senior men's 200m when Todd Johnston (Ariki) will be pitted against Nick Bolton (Christchurch Old Boys) and David Elliott (University of Canterbury).
Rhian Ward (Alexandra), a member of the New Zealand team at the Sydney Youth Olympics last month, is favoured to win the senior men's 800m.
A feature of athletics this season has been the increasing numbers competing in the throwing events, probably reflecting boosted interest following Valerie Adams' golden Olympic double.
Athletes to watch today include Paralympian Rory McSweeney in the senior men's javelin, Raylene Bates in the masters women's shot put and senior women's discus, and Dean Rusbatch and Todd Bates in the junior men's shot put.
The main two days of the Otago championships will be held today and next Saturday. The combined events, 10,000m and some hammer throws have already been held. The remaining hammer throw events will be held on March 2 and the 5000m championships on March 10.
