He rode the Gill Duffield-trained AF Alghabra, the six-year-old and only mare in the field, to land the 1600m feature to register an eighth career win for her owner/breeder Khalid Khalifa Al Nabooda.
Duffield was delighted: "That is brilliant; she is such an amazing mare and so very tough. She won her only previous start here so we knew conditions were fine but she had a lot to find on ratings against some genuine Group performers. I could not be more pleased and Tadhg has given her a great ride."
O'Shea was completing a double having won the opening 1400m Ford Taurus Trophy on Al Sharood for trainer Doug Watson who also enjoyed a great evening. The three-year-old, the only filly in the line-up, was sent for home over 400m out and never looked likely to be caught.
O'Shea explained: "She is a really nice filly and we would have to hope that she can be competitive at the [Dubai World Cup] Carnival. The Cape Verdi is a fillies only race that really should suit her back on turf. She was getting tired close home but was entitled to on her first start for a while."
O'Shea completed the treble on Watson's Mark To Market who prevailed in the closest finish of the Meydan season to date in the 1400m Ford Fusion Trophy. O'Shea drove his mount to lead in the very last stride and deny long-time leader Lord Tiger.
There was quite a delay before the judge announced the verdict, by the minimum margin of a nose and to the delight of the assembled members of Emirates Entertainment racing Club (EERC) in whose colours he runs.
O'Shea said: "I was not sure but knew it was very close; my fellow's head was down when we hit the line and that has proved decisive."
Watson then completed his own treble and a double for EERC when Clasp landed the following 1600m Ford Mustang Trophy under Pat Dobbs who was opening his account for the season.
Watson said: "It has been a good meeting and we knew we had a few chances. Clasp really deserves that after some good runs in defeat. He will be ten in January and has been a great horse for all of us. It is nice for the owners as well as they did not have much luck last season but are enjoying a good run at the moment."
Racing concluded with the 2000m Ford Edge Trophy which was won by UAE debutant Jamr, ridden by Xavier Ziani for trainer Mubarak bin Shafya.