Frankel's brother Noble Mission will step up to Group One level for the first time when he runs in the Gold Cup at The Curragh.

His owner Khalid Abdullah paid a 21,000 ($A31,498) to add him to Sunday's field and trainer Lady Cecil is confident he up to the task.

"Noble Mission has made an excellent start to the season," she said on her website.

"We felt he had done very well through the winter and we've been delighted with how he has performed so far in 2014.

"He has earned the right to contest a Group One - hence the decision to supplement for the Tattersalls Gold Cup. The likelihood of there being some ease in the ground came into our thinking, although he seems to go on any ground.

Aidan O'Brien has won the race six times and his three contenders are Ruler Of The World, Magician and Hall Of Mirrors.

Jim Bolger also has a numerically strong hand with Einsteins Folly, Parish Hall and Trading Leather all in the mix.

Dual Melbourne Cup placegetter Red Cadeaux is also still in the mix.