Boxer Amit Panghal, the world No. 1 in men's 52kg, crashed out of the Tokyo Olympics, losing to Yuberjen Herney Martinez Rivas of Colombia in a Round-of-16 bout on Saturday.Panghal, India's biggest hope in this section, lost 5-0 on points, starting the day on a disappointing note for boxing after the high of Lovlina Borgohain reaching the semifinals and assuring a medal for the country.Panghal, the 2018 Asian Games gold medallist, had drawn a tough opponent in Martinez Rivas, the silver medallist at the Rio Olympics in 2016.The 25-year-old Indian from Haryana started off well and won the first round. Starting with an open stance and moving around the ring, Panghal made Martinez Rivas come for him and make him work for his points.Panghal counter-attacked on all possible occasions and landed some good combinations, winning a split decision 4-1 in his favour.But Panghal changed his tactics inexplicably in the second round and became too defensive, maybe hoping to make Martinez Rivas work hard for points so as to tire down the Colombian.Martinez Rivas won the second round, getting 10 points from all five judges.Panghal, whose fitness looked suspect, looked totally exhausted and could not do much in the third and final round as he tried to go after his rival in the last 30 seconds but that was too late and too little as the judges had by that time seen Martinez Rivas attacking a lot in the right through the round.Martinez Rivas bagged 10 points from all five judges while one judge gave Panghal eight points while others gave him nine each.Panghal's defensive approach -- whether it was by design or due to lack of fitness -- in the second round undid all his efforts of the last five years.