Dai Greene's bid for Olympic gold ended in disappointment as he had to settle for an agonising fourth place in the 400 metres final tonight.
The Welshman, the world champion, was never in the race running from lane three and, although he finished strongly, was not able to make up the ground he lost in the first half of the race.
He finished in 48.24 seconds, 0.14secs off a medal
Felix Sanchez, the 34-year-old from the Dominican Republic, took gold eight years after winning the title in 2004 in 47.63s.
American Michael Tinsley took the silver in 47.91, a personal best, while favourite Javier Culson of Puerto Rico was third.
Victory was always going to be a tall order for Britain's athletics team captain after he only scrapped into the final as a fastest loser.
The 26-year-old admitted he had been disgusted with his semi-final showing, saying he was determined to make amends in the final, and at least produced a better run.
His season has not gone smoothly, with knee surgery in the winter and then a virus hampering his preparation.
Greene told BBC1: "I just felt a bit tired tonight. Obviously it was a big shock in the semi-final - I was surprised everyone went that fast.
"I gave it everything I had tonight. A bit better structure to my race but I was just a bit too tired at the end there and narrowly missed out."
On the injuries which troubled him over the winter, he said: "It certainly affected my build-up - it meant I couldn't start until halfway through January instead of October time, but I I can't argue too much, I had a personal best a few weeks ago.
"I just think perhaps the endurance wasn't quite there for the rounds which shows I missed some of the winter work. You can't always tell if it's there or not until you get into these majors.
"I was just found wanting a bit at the end but I couldn't have given anything else tonight."
Greene was surprised by the pace his rivals produced throughout the event.
He said: "I know coming in that me and Culson were way ahead in the rankings, but I've never been in a competition or a race before where people have gone far above their expectation until Saturday night, when everyone seemed to surprise me.
"It sort of felt slightly [like that] again tonight - a few of the guys really pulled something out.
"They're great competitors, you cant take anything away from them, they've worked very hard.
"Felix is a fantastic athlete and a worthy winner on the day."
Holly Bleasdale's hopes for an Olympic medal also ended in bitter disappointment as nerves appeared to get the better of her on the big stage.
The 20-year-old from Lancashire was on the verge of tears as she failed her third and final attempt at 4.55m, well below her best this summer of 4.71m.
She looked nervous as soon as she was introduced to the crowd and almost went out at 4.45m, needing three attempts to clear her opening height.
Bleasdale was clearly fired up, punching the air with relief and delight when she finally cleared 4.45m.
But she was unable to steady herself from there, bailing out on her second attempt at the next height.
She said: "The conditions weren't great, it was really bad headwind.
"I'm really disappointed with how I did.
"I felt like I could have jumped around 4.70m but I struggled to cope with the conditions.
"I am trying to look at the positives and to finish in the top eight in my first Olympic final is pretty good, but I am just heartbroken with how it went today.
"I am only 20 and I feel like I could have performed well this year."
There was relief for Perri Shakes-Drayton in the 400m hurdles as she just made it through to the final as a fastest loser.
The east Londoner, joint second in the world rankings, clocked 55.19 seconds to finish third in her heat and it looked like that time would not be good enough only for a disqualification to send her through.
Eilidh Child went out, finishing seventh in 56.03secs.
Shakes-Drayton said: "I'm through, it's a bit emotional because I thought I was out. I've got a day's rest, and hopefully [I can] redeem myself and do something."
Child said: "My stride pattern didn't go to plan. I am gutted I never left it on the track. I have come off thinking I could have done a lot better.
"I got my strides wrong at hurdle three and from then on I was just trying to get it back."
Belarus' Nadzeya Ostapchuk won the first gold medal of the night, throwing 21.36m to become Olympic shot put champion.
The 31-year-old took the title from New Zealand's Valerie Adams, who had to settle for silver in 20.70m.
Russian Evgeniia Kolodko took the bronze with 20.48m.
Yuliya Zaripova took gold in the women's 3,000m steeplechase, clocking a new personal best of 9:06.72.
The Russian was an impressive winner, streaking clear down the home straight to cross the line ahead of Tunisia's Habiba Ghribi.
Ethiopian Sofia Assefa took bronze.
Great Britain's Margaret Adeoye set a new personal best to qualify for the 200m semi-finals.
The 27-year-old dipped under 23 seconds for the first time, looking strong to hold off challengers down the home straight and clock 22.94 in third place.
Abi Oyepitan was even more impressive as she finished second to American Carmelita Jeter in 22.92 in her heat.
Adeoye said: "I couldn't sleep last night. I kept on picturing my race in my head, going over it and over it and then in the morning the picture had changed so I started panicking.
"But I just did what I had in my head and I seemed to do well."
Oyepitan, 32, was critical of her run, saying: "I need to run a hell of a lot faster than that, but I think I can do it if I execute better."
Anyika Onuora, as was the case in the 100m, failed to make it past the first round, finishing fourth in her heat in 23.23 and missing out in a fastest loser spot.
She said: "I just tightened up a little bit before the end which cost me a place in the semi-final."
Nineteen-year-old Kirani James stormed to 400m gold, destroying the field to win in 43.94.
No one came close to catching the teenager from Grenada down the home straight as he crossed the line well ahead of another 19-year-old, Luguelin Santos of the Dominican Republic.
Trinidadian Lalonde Gordon took the bronze.
American Jennifer Suhr dethroned Yelena Isinbayeva as pole vault queen by taking gold in 4.75m
She won on countback from Cuban Yarisley Silva, while the great Russian, who had been two-time reigning Olympic champion and is the world record holder, had to settle for bronze.
There was further late disappointment for the hosts.
Shakes-Drayton lost her place in the final when the Czech athlete disqualified for a trailing leg infringement, Denisa Rosolova, was reinstated after a protest, taking back the Briton's place in the medal race.