Australian Peter Senior leads the Senior Tour challenge after the first round of the Senior PGA Championship presented by Kitchenaid in Missouri.
Americans Jay Haas and Duffy Waldorf lead the way at Bellerive on five under par, with Senior two shots further back after a three under par 68 which left him tied for fifth.
Senior, whose only Senior Tour title to date came in 2011 on home soil, carded four birdies against a solitary dropped shot.
Scotland’s Andrew Oldcorn and five-time Open Champion Tom Watson are amongst those on two under, with Sandy Lyle and Mark McNulty five off the pace on level par.
England’s Roger Chapman began the defence of his title with a one over par 72.