Dublin - Ireland lock Iain Henderson looks set to miss at least half of the Six Nations after surgery on a torn ligament in his thumb on Monday.
His Ulster province expected him to be sidelined for about 10 weeks.
Henderson scored two tries for Ulster on Friday in beating Scarlets 30-15 in the European Champions Cup.
By having the surgery now, Henderson hopes to be well recovered by the time of the Rugby World Cup in Japan in September.
He stands to miss Six Nations games in February against England, Scotland, and Italy. He could be available in March to face France and Wales.