The two are the only unbeaten teams in the tournament, but England have been more impressive in their outings to date, beating Italy and Wales 17-0 and 28-16 respectively.
Ireland snatched a late victory when they beat France 9-6 in the opener three weeks ago, and they also had to work hard to escape with a 29-23 win over Italy.
Clarke has made three changes in a bid to “freshen and strengthen” the team; Matthew Healy makes a start at scrum half, Ronan O’Mahony is promoted to a place on the right wing and James Sandford moves up from the bench to the second row.
Clarke said: “The game against England will test how far we have progressed as a squad. Preparation has gone well and the mood in the camp is very good. We are aware of the challenge ahead and the level of performance required, both from a team and individual viewpoint.”
Despite eventually cruising to victory, England are concerned at a lack of fluency shown in midfield against Wales; accordingly they have called up the Harlequins centre George Lowe from outside the ranks of the 32-strong elite player squad. He forms a new pairing with Tom Casson (Saracens) as England make six changes to the side that took the field against Wales.
Lowe and Casson complete a new-look back line trio with Rory Clegg replacing Newcastle Falcons teammate Rob Miller at fly half, while Leicester’s Greig Tonks switches from centre to full back in place of Tom Homer (London Irish).
Up front, Gloucester’s Shaun Knight wins a first start at tight-head after displacing Bob Baker (Wasps) and lock Peter Elder (Wasps) is in the second row in place of Worcester’s Graham Kitchener.
England coach Mark Mapletoft may feel his team should be good enough to win, but he is under no illusions either and has done some homework on Ireland’s record in the Midlands. He pointed out that Ireland had only lost once in four years at Dubarry Park.
“They seem to have found a suitable permanent and happy home in Athlone,” he said. “Our boys have been very positive in the work they’ve done so far this week and the emphasis has been on quality on the training ground, and being physically and mentally ready for a big challenge. Ireland are a very competitive side at home.
“We know there will be a decent crowd and a passionate atmosphere so we have to be fully prepared.”
IRELAND: D Kearney (Lansdowne/Leinster), R O’Mahony (Garryowen/Munster), I McKinley (UCD/Leinster), E Sheridan (Lansdowne/Leinster), M Keating (Clontarf/Leinster), I Madigan (Blackrock/Leinster), M Healy (Lansdowne/Leinster), P McAllister (Ballynahinch/Ulster), T Sexton (Old Belvedere/Leinster), J McGrath (St Mary’s/Leinster), C Ruddock (Neath/Exiles), J Sandford (Queens/Ulster), R Ruddock (Millfield School/Exiles), D Ryan (Lansdowne/Leinster), P O’Mahony (capt, Cork Con/Munster). Replacements: D McGregor (Ballynahinch/Ulster), J O’Connell (Lansdowne/Leinster), M Flanagan (UCD/Leinster), M Noone (Seapoint/Leinster), C Murray (Garryowen/Munster), S Gahan (Lansdowne/Leinster), G Foley (Blackrock/Leinster).
ENGLAND: G Tonks (Leicester), S Stegmann, G Lowe (both Harlequins), T Casson (Saracens), W Hurrell (Leicester), R Clegg (Newcastle), D White (Leeds), B Moon (Exeter), J George (Saracens), S Knight (Gloucester), J Gaskell (Sale), P Elder (London), J Ovens (Bath), C Clark (capt, Leeds); C York (Harlequins). Replacements: A Ellis, B Baker (both Wasps), C Fearns (Sale), T Sargeant (Harlequins), S Harrison (Leicester), F Burns (Gloucester), J Short (Saracens).