Sexton Six Nations concern after another concussion

(Reuters) - Johnny Sexton, the conductor of Ireland's back-to-back Six Nations triumphs, is an injury worry for this season's tournament after again suffering concussion in Leinster's Champions Cup defeat by Wasps on Saturday. The flyhalf, key to Ireland's hopes of becoming the first team ever to win the Six Nations (and the old Five Nations) outright three times in succession, was forced off after nine minutes of Leinster's record 51-10 defeat. It followed a clash of heads with his old Leinster