Clarke hoping unbeaten Ireland withstand stern England test
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.