Ireland powered past Six Nations rivals Scotland 27-3 to put themselves in the box seat to reach the quarter-finals at the Rugby World Cup on Sunday.

Three push-over tries in the first half did the damage before wing Andrew Conway grabbed a fourth after the break to secure a bonus-point win, with games to come against Japan, Russia and Samoa in Pool A.

“We started really well – we were positive, we wanted to attack,” said Ireland captain Rory Best.

“Obviously with the conditions in the second half it became a bit more of an arm-wrestle but we know how good a team they are and we’re delighted with that win.”

With a sea of green-clad Ireland supporters dominating the stands at a packed but wet International Stadium Yokohama, Ireland were in no mood to be nice to their Six Nations rivals.

In a brutally physical game, in which the medics were rushed off their feet, Ireland bossed the breakdown and held a commanding 19-3 lead at half-time.

As the rain’s intensity increased in the second half it was Ireland who relished the deteriorating weather most with a further eight points.

Conor Murray was given a dream ride behind a rampant forward pack, directing traffic with aplomb, particularly with an on-target kicking game, and pre-match concerns about Ireland’s injury-hit backline quickly evaporated.

Scotland, meanwhile, did not help themselves with a weak defensive effort while being unable to penetrate the green wall in front of them.

The bonus-point win put Ireland level with hosts Japan with their first-round victories in Pool A, and the two go head-to-head next weekend.

James Ryan, Rory Best, Tadhg Furlong and Conway scored for Ireland with Johnny Sexton and Murray landing a conversion each and Jack Carty kicked a penalty.

For Scotland, Greig Laidlaw’s first-half penalty was their only score.

There was concern in the Scotland camp about Hamish Watson who was stretchered off just before half-time with a knee injury.

The outstanding flanker had made 14 tackles up to that point in the face of a constant wave of green attacks.

Bundee Aki and Josh van der Flier required blood-bin treatment with Aki failing a head knock assessment.

Peter O’Mahony also required a head injury assessment and Murray took over Ireland’s kicking duties when Sexton was being treated for a knock.