Gordon Greenidge and Frank Worrell
Even if I did cheat with the Bradman call, Worrell actually did open a fair amount, having batted just about everywhere in the order for at least a few matches, because he batted wherever the Windies needed him to. On the 1957 tour of England, he carried his bat for 191* against an attack of Statham, Trueman, Laker and Bailey at Trent Bridge. (He also opened the bowling in that match). That's before you get to his captaincy.