The invention relates to a top piston ring (4) for use in a piston ring pack in a groove (3) in a piston (1) of a large two-stroke turbo charged uniflow-scavenged internal combustion engine with crossheads. The top piston ring comprises a ring body with an upper ring face (16), a lower ring face (17), an outer ring face (11), an inner ring face (12) and first-and second engaging end portions (8,9) at a ring partition. The first engaging end portion (8) comprises a circumferentially extending finger (23), the second engaging end portion (9) comprising an circumferentially extending recess (28) shaped and sized for sealingly and slidably receiving the finger. The circumferential extend of the recess is divided in a proximal portion (46) and a distal portion (47). The circumferential extend of the finger is divided in a proximal portion (44) and a distal portion. The proximal portion of the recess opens to the outer ring face and to the lower ring face.
