London Irish face Rotherham in Sunday's Powergen Cup quarter-final expecting as tough a match as they were given by French giants Toulouse last weekend.

The cup holders beat the former European champions and Heineken Cup favourites at the Madejski Stadium.

But they are just as wary of the threat posed by the National League One promotion contenders after the Yorkshiremen ambushed Bristol in the last 16.

"Rotherham are tough, tough opposition," said the Exiles' director of rugby, Conor O'Shea.

The former Ireland full-back's verdict is based on the underdogs' unbeaten record in all competitions, which stretches back over 34 matches to December 2001.

We know we shouldn't win, but we knew we shouldn't have won against Bristol, so anything can happen Jim Kilfoyle Rotherham chief executive

The highlight of that run was December's 24-19 win at Bristol in the last round of the cup, which confirmed their Premiership potential.

O'Shea insists Irish will have to reach the same standards as they managed against Toulouse to avoid another upset.

"Rotherham are well-drilled and well-oiled, and everything just blasts off," he said.

"They are a really, really strong rugby side - physical up front with some great backs.

"If we come out and play to our best, then we will beat them, but we need to play 100% to our best.

"There will be no underestimating what we are facing. It will get full metal jacket."

Irish make several changes to the side that beat Toulouse, with Michael Horak returning on the left wing after injury and Nick Kennedy coming into the second row.

Rotherham show only one alteration from their last match, with Leon Greef shaking off a knee injury to return to the back row.

The Yorkshire side's chief executive, Jim Kilfoyle, knows the odds are stacked against his team, but believes another upset is possible.

"I know it sounds a cliche, but matches like this are what the magic of the cup is all about," he said.

"We know we shouldn't win, but we knew we shouldn't have won against Bristol, so anything can happen."

London Irish: Mapletoft; Sackey, Burrows, Venter, Horak; Everitt, Martens; Worsley, Drotske, Halford, Casey, Kennedy, Gustard (capt), Danaher, Sheasby.
Replacements: Barrett, Appleford, Dawson, Kirke, Delaney, Hatley, Hardwick.

Rotherham: Benson; S Wood, Oliver, Umaga, M Wood; Pez, Rauluni; Lloyd, Toews, Noon, Cook, Kenworthy, Greef, Spence, Schmid.
Replacements: Gravil, Bunting, Giacheri, Remnant, Harrison, Cannon, Ewens, Cundick, Scully.