The 51st National Open Athletics begins in Kolkata on Saturday. Triple jumper Mayookha Johny and shotputter Om Prakash Singh will be the star attractions at the 4-day event. Reigning champions Indian Railways will be among the 30 teams from states, union territories, boards and institutions who will vie for top honours at the meet. Organisers Bengal Athletic Association said, a total of 880 athletes including 580 men will compete in 22 events each in men's and women's sections.