Buttar, of Kindersley, Sask., and Vieira both scored 88.00 in their second performances.
Mike Lee of the United States was third after scoring an 87.50 and leads the overall standings. Buttar is second and Vieira third.
American Tanner Aus recorded the best score in the second bareback performance with an 86.50. Clint Laye of Cadogan, Alta., is first overall.
Tanner Milan, K.C. Jones and Kyle Irwin all scored 4.2 in the steer wrestling. Milan, of Cochrane, Alta., leads the standings.
Rusty Wright and Cody DeMoss, both of the U.S., scored 87.50 in the saddle bronc. DeMoss leads all riders.
American Marty Yates managed the lowest score in the tie down roping with a 6.8 while New Zealand's Carmel Wright had a 17.72 in the ladies barrel racing.