The invention relates to a pump, particularly a high-pressure fuel pump, having a drive shaft, which includes a section that is eccentric to the rotational axis thereof and on which a ring is rotatably supported. The pump has at least one pump piston, which is directly supported on the ring via the piston base thereof, or via a support element and is driven in a stroke movement upon the rotational movement of the drive shaft. The ring has an at least approximately planar contact surface in the region of the support of the piston base or of the support element, and the support surface of the piston base or of the support element on the ring is greater than the cross-sectional surface of the shaft of the pump piston. The extension of the support surface of the piston base or of the support element in the tangential direction to the rotational axis of the drive shaft is greater than the extension thereof in the direction of the rotational axis of the drive shaft.