that season. Bolt entered the World Championships to defend his sprint titles but was not the comfortable favourite he had been since 2008. In the World Championships 100 m, Bolt won his semi-final in 9.96, which lagged Gatlin's semi-final win in 9.77 seconds. However, Gatlin did not match that form in the final while Bolt improved through the rounds. In a narrow victory, Bolt leaned at the line to beat Gatlin 9.79 to 9.80 seconds. Bolt joined Carl Lewis and Maurice Greene on a record three 100 m world titles. A similar outcome followed in the 200 m World finals. In the semi-final, Gatlin outpaced Bolt – the Jamaican at 19.95 and the American at 19.87. Despite such slow times prior to Beijing, Bolt delivered in the final with his fifth fastest run ever for the 200 m at 19.55 seconds. Gatlin failed to reach his early season form and finished almost two-tenths of a second behind Bolt. Bolt's four consecutive wins over 200 m at the World Championships was unprecedented and established him clearly as the best ever sprinter at the competition. There was also a fourth straight win in the 4 × 100 metres relay with the Jamaica team (Nesta Carter, Asafa Powell, Nickel Ashmeade, Usain Bolt). The Americans initially had a lead, but a poor baton exchange saw them disqualified and Jamaica defend their title in 37.36 seconds – well clear of the Chinese team who took a surprise silver for the host nation. Conscious of his injuries at the start of the season, he did not compete after the World Championships, skipping the 2015 IAAF Diamond League final. 2016 Rio Olympics Bolt competed sparingly in the 200 m before the Olympics, with a run of 19.89 seconds to win at the London Grand Prix being his sole run of note over that distance. He had four races over 100 m, though only one was in Europe, and his best of 9.88 seconds in Kingston placed him fourth on the world seasonal rankings. As in the previous season, Gatlin appeared to be in better form, having seasonal bests of 9.80 and 19.75 seconds to rank first and second in the sprints. Doping in athletics was a prime topic before the 2016 Rio Olympics, given the banning of the Russian track and field team for state doping, and Bolt commented that he had no problem with doping controls: