Two days of gruelling competition came down to two crucial seconds in the final 800m race, as Belgian pretender Nafissatou Thiam usurped Jessica Ennis-Hill as Olympic heptathlon champion.

At the end of a gripping competition, Thiam went into the two-lap race with a 142-point lead over the defending champion. Given the duo's personal bests over 800m, that equated to Thiam getting around within 9.47sec of Ennis-Hill to claim victory.

Although the Briton produced a sterling gun-to-tape showing, Thiam came in 7.47sec behind to ensure gold by the narrowest of margins.

"I went into the 800m knowing I had about nine or 10 seconds on Jessica," said the 21-year-old Thiam, whose gold was only Belgium's fourth athletics medal and first since 2008. "I just tried to do my best and have no regrets so I could leave thinking I gave it all."

Thiam said she had not expected a gold in Rio. "It's more than a dream to be Olympic champion. I injured my elbow six weeks ago throwing the javelin in the Belgian championships. At first the doctor was not very optimistic about it. I did a lot of work with the physio. They said I had to go through the pain but if I was throwing correctly it would be okay."

Thiam added: "I wasn't expecting to win - maybe top eight, but not the gold."

Ennis-Hill finished just 35 points adrift of Thiam's winning total of 6,810 points, with Canada's Brianne Thiesen-Eaton claiming bronze (6,653).