The mechanics of the movement are the same, just that you hold the bar with pronated grip. (fitnessandpower.com)
Hold the bar tightly using pronated grip with your hands slightly wider than shoulder width. (fitnessandpower.com)
One of the problems you might encounter with the Close Grip Barbell Bench Press is shoulder joint pain... the closer - in position can put more stress on the joints, especially when the hands are in the normal pronated grip on the bar. (thebestexercises.com)