Christine Ohuruogu could not hide her disappointment after she was beaten into second place in the 400m final at London 2012.
Ohuruogu 'stunned' to lose title
She finished strongly in a season's best time of 49.70 seconds but it was not enough to earn another athletics gold for Great Britain.
American Sanya Richards-Ross claimed gold in a time of 49.55secs, while compatriot DeeDee Trotter took bronze.
"I was stunned. I was heartbroken actually, I really was," said Ohuruogu.
"Christine Ohuruogu was always in the right place in case anyone faltered but she could have won it because Richards-Ross didn't run the best race of her life. It all came down to the dip at the very end. It was a great finish for Christine and I am sure she will be happy with the silver medal."
She added: "To lose your title like that, it was tough. But Sanya's a worthy competitor and she ran a good race so I have to be happy with what I got. It could have been worse."
The 28-year-old Londoner was just eight hundredths of a second slower than the time she
ran in Beijing to win gold four years ago.
"I thought I still had some time but the line came too soon and I thought, 'No, it's gone, it's gone'.
"I came here with one thing and one thing only on my mind and that was to continue my reign as Olympic champ. I'm just a bit disappointed."