Canada take men's sprint relay gold as botched changeover scuppers USA
Andre de Grasse ran a superb last leg to bring the Tokyo silver medallists home in 37.50 seconds for their second gold in the event following their 1996 win.
Akani Simbine, the nearly man of the individual 100 metres, ran a terrific last leg to get South Africa silver in an African record 37.57, as did Zharnel Hughes to earn Britain bronze in 37.61. Hughes was in the team that finished second in Tokyo but was later stripped of the medal due to a doping offence by teammate CJ Ujah.
The US failure was the latest in a long series as they have not won the event they used to dominate since 2000.
Christian Coleman gave them a great start but ended up virtually colliding with Kenny Bednarek at the first handover. They recovered to finish well down the field, but were disqualified as the exchange was illegal.
Since 1995, in the Olympics and World Championships, the US have now had 11 dropped batons, disqualifications or bans.
