55th National Open Athletics Championship gets underway at SAI Complex in Kolkata today. India's top athletes, including the Olympics-bound trio of Inderjeet Singh, Lalita Babar and Tintu Luka, will vie for honours at the event. The showpiece meet of the Indian athletics calendar will be a big opportunity for the top athletes not only to achieve Olympics mark but also to make their respective states and departments proud. While all eyes would be on the Rio-bound trio, the marquee meet will also mark an emotional return to action for 19-year old sprinter Dutee Chand after successfully fighting off gender controversy. The sprinter from Odisha was cleared by the Court of Arbitration for Sport in July to compete in national and international events after challenging world body of the sport IAAF's policy on hyperandrogenism.Dutee Chand who had bagged the 100 metre and 200 metre gold in the National Open in Ranchi two years ago, missed out on the last edition in Delhi with the ban. With country's top athletes in their roster, heavyweights Railways and Services once again expected to dominate the show, even as states like Kerala, Uttar Pradesh, Haryana and Punjab will look to have their share of medals. The four-day event, which will have competitions in 44 events in men's and women's sections, will see more than 900 athletes from across 28 states and eight Boards in actions. Railways also boast of the duo of Lalita and Tintu who have already made the cut for next year's Rio Olympics. Five gold medals will be up for grabs today that will begin with men's and women's 5000 metres, while women's shot put, long jump and hammer throw finals will be held in the afternoon following the official inauguration.