A piston ring (6) which is arranged with radial and axial play in an associated piston ring groove (5) in a piston (1) of a reciprocating internal combustion engine can be stabilized to prevent tilting on and contact with the radially outer edge of the piston ring groove (5) by the cross section of the piston ring (6) and/or the piston ring groove (5) being designed in such a manner that a gap is formed between the lower side of the piston ring (6) and the lower supporting surface of the associated piston ring groove (5), said gap opening vertically radially outwards in the radial direction and, when the piston ring (6) is not subjected to a load, remaining open to the outside irrespective of the temperature of the piston (1) for as long as the piston ring (6) is not loaded by pressure on the top side. The effect achieved by this is that, when a piston (1) is deformed under the action of heat during operation, the initial contact between the lower side of the piston ring (6) and the opposite, lower supporting surface of the piston ring groove (5) begins at least in a region of the lower side of the piston ring (6), which region faces the piston axis, and rubbing of the piston ring (6) on the radially outer edge of the piston ring groove (5) is prevented.