Aidan O'Brien all set to unleash staying big guns on Friday

Aidan O’Brien’s Gold Cup plans will become clearer on Friday with both Kyprios and Tower Of London in action.

Kyprios is favourite for the Ascot showpiece, having missed the chance to add to his 2022 victory in the race through injury last year.

He has returned to action as good as ever, going down gallantly in defeat in both the Irish St Leger and Long Distance Cup on Champions Day at the end of last season, before a straightforward success at prohibitive odds in last month’s Vintage Crop Stakes.

Tower Of London, meanwhile, is the new kid on the block in the staying division.

Fourth to stablemate Continuous in the St Leger, he was a beaten favourite in the Irish Cesarewitch but has looked an improved performer in winning twice overseas.

First he came from an uncompromising position to win the Red Sea Turf Handicap in Saudi Arabia and then won the Dubai Gold Cup like a very good horse, quickening up stylishly.

Kyprios follows O’Brien’s tried and tested route going from the Vintage Crop to the Saval Beg Levmoss Stakes at Leopardstown, while Tower Of London takes in the Boodles Yorkshire Cup on the Knavesmire.

"We’ve been very happy with Tower Of London really," said O’Brien.

"He’s progressing well. He ran a nice race in the St Leger, but has shown in his last two races that he’s improving quickly.

"He did well to win in Saudi when he met some trouble, but then in Dubai what he did was really pleasing."

Tower Of London faces Willie Mullins’ Vauban, having his first run since disappointing in the Melbourne Cup, Royal Ascot winner Gregory, Giavellotto, winner of the race 12 months ago, the William Haggas pair of Hamish and Naqeeb and Al Qareem from Karl Burke’s yard.

Kyprios clashes with stablemate Queenstown, who chased him home in