Jonathan Sexton passed fit to start for Ireland against Argentina

• No10 overcomes groin injury to take place for quarter-final on Sunday• Paul O’Connell, Peter O’Mahony and Sean O’Brien ruled out for key clashJohnny Sexton has convinced Ireland to start him in Sunday’s World Cup quarter-final against Argentina despite lingering concerns over a groin injury. Ireland have opted to gamble on throwing in their linchpin fly-half from the start against the Pumas in Cardiff, even though the Leinster fly-half has fought a fitness battle all week.Sexton trudged out of Ireland’s 24-9 victory over France at the Millennium Stadium after just 25 minutes last weekend, th…