Saturday's Irish Derby has been dealt a blow with the news that US Army Ranger will not run.

The Aidan O'Brien-trained Epsom Derby runner-up had been heavily backed for the Curragh classic earlier this week and was as low as even-money to reverse the form with his Epsom conqueror Harzand.

However, O'Brien reported on Wednesday afternoon that the colt had scoped poorly and would miss the race. Stable jockey Ryan Moore is now expected to switch to Idaho, who finished third at Epsom.

"His scope just wasn't 100% clean today," said O'Brien. "Obviously it's a big pity. He'll have a little rest now and we'll see where we go from there."

Today's news sees Harzand return to favouritism but only just. Bookmakers generally offer 5/4 about Harzand with Idaho close behind at 6/4. Harzand's trainer Dermot Weld has yet to confirm the Derby winner's participation as the colt continues to recover from his Epsom exertions.

The supplemented Red Verdon is general third favourite at around 8/1.