Usain Bolt laughs his way over the finish line to win gold

Usain Bolt has made Olympic history as he raced to his third Olympic gold medal in a row.

Bolt was slow out of the gates and trailed for half of the race, but managed to reel in American Justin Gaitlin and win his third straight 100 meter gold.

He clocked a winning time of 9.81 seconds ahead of Gatlin (9.89) and bronze medallist Andre de Grasse from Canada (9.91).

Bolt, who turns 30 on the day of the closing ceremony in Rio, had the race well in hand with 20 metres to run.

The 34-year-old Gatlin, who was the oldest runner in the final, is a highly divisive figure in the sport, having twice served doping bans.

The 2004 Olympic champion has now finished second to Bolt in the 100m at the 2012 and 2016 Olympics and the two most recent world championships.

Gatlin will be forever haunted by his sluggish time after he ran a 9.80 at the U.S. Trials just six weeks ago.

BOLT'S 100M WINNING TIMES AT MAJOR EVENTS

9.69 - 2008 Beijing Olympics (world record)

9.58 - 2009 Berlin world championships (world record)

9.63 - 2012 London Olympics (Olympic record)

9.77 - 2013 Moscow world championships

9.79 - 2015 Beijing world championships

9.81 - 2016 Rio Olympics 

Newshub.