Kobe - Ireland have called Jordi Murphy into their Rugby World Cup squad in Japan after back-row Jack Conan was ruled out of the remainder of the tournament with a broken foot.

Leinster loose forward Conan suffered his foot injury while training on Thursday, and then had to withdraw from the starting side beaten 19-12 by Japan in Shizuoka on Saturday as the hosts pulled off one of the great upset wins at a World Cup.

Ulster back-row Murphy will now head straight to Kobe, where Ireland face rank outsiders Russia on Thursday after the Shizuoka shock opened up the race for quarter-final qualification from Pool A.

"Jack Conan has been ruled out of the remainder of Rugby World Cup 2019 with a foot injury," said an Irish Rugby Football Union (IRFU) statement issued Sunday.

"He will be replaced in the Ireland squad by Jordi Murphy.

"Jordi will arrive in Japan on Sunday, and will join the Ireland squad in Kobe as they prepare for Thursday's Pool A game against Russia."

Saturday's result saw Japan carry on from where they left off with their 'Miracle of Brighton' 34-32 win over South Africa at the 2015 World Cup in England.

While Ireland, who could yet reach the last eight, should be too strong for Russia, they could also be without Rob Kearney after the fullback failed a Head Injury Assessment (HIA) during the loss to Japan.

"Unfortunately Jack Conan has a fracture in his foot, and he will return home to Ireland," said Ireland coach Joe Schmidt immediately following Saturday's match.

"Rob Kearney has got a decent shiner, but he's feeling okay now. He failed his HIA as far as I know. If he doesn't pass HIA two and three he will be a confirmed concussion and he would miss the Russia match."

One consolation for Ireland, who overwhelmed old rivals Scotland 27-3 in their opening match of this tournament, from the Japan defeat was that they managed a losing bonus-point.

That could yet prove important if they are to emerge as one of two qualifiers from Pool A.

"Potentially the losing bonus-point could be really important, it means we have six points from two pool games so far," said Schmidt.

"Japan have nine points, and then Samoa have five," added the New Zealander.

"Keeping that bonus-point allowed us to stay in front of Samoa (who play Scotland on Monday) in the short term."