Former Olympic Champion Lord Sebastian Coe has been elected president of the International Association of Athletics Federations (IAAF).
Lord Coe succeeds Lamine Diack, the 82-year-old from Senegal, who has been president since 1999, and becomes only the sixth president in the IAAF's 103-year history.
The London 2012 Games chairman edged out Ukrainian pole vaulter Sergey Bubka in a vote at the IAAF Congress in Beijing. Coe won 115 votes, with Bubka receiving 92.
The 58-year-old takes over athletics' world governing body at one of the most difficult moments in its history, following recent allegations - which it denies - that a blind eye was turned to suspicious blood test results from hundreds of athletes and that it also blocked the publication of a report claiming a third of athletes at the 2011 World Championships in South Korea admitted doping.
Lord Coe, who has been backed by Mo Farah to "change athletics", has promised to set up an independent anti-doping agency for the sport inside his first 100 days in office.
Speaking at a news conference in Beijing after being elected, Lord Coe said "there is a zero tolerance to the abuse of doping in my sport and I will maintain that to the very highest level of vigilance."
He had previously described the allegations as a "declaration of war" on the sport.
Despite strong rebuttals from the world athletics high command, it is clear that some damage has been done to the sport's reputation, and Coe will be expected to tackle it urgently in order to restore credibility to the organisation.
Coe - who has stepped up from Vice President - delivered a powerful speech to the Congress ahead of the vote in which he said: "There is no task in my life for which I've ever been better prepared, no job I've ever wanted to do more and with greater commitment."
His election was welcomed by Prime Minister David Cameron and marathon runner Paula Radcliffe.