Jessica Judd was left distraught by today's World Championship exit, calling her 800 metres heat was a “disaster”.
The 18-year-old has enjoyed a remarkable rise to prominence this season, winning the European Team Championships and then breaking the two-minute mark to win the Sainsbury's Grand Prix a week later.
Judd had hoped to continue that progression today, only to fall just short of a semi-final berth at the Luzhniki Stadium.
The Canvey Island athlete crossed the line fifth in her heat after a 2 minutes 4.08 seconds run on her senior Great Britain debut - a result that hit her hard.
"It just didn't go how I wanted it to at all," Judd, who has battled problems with her ankle and hip recently, said.
"I've come along way this season, it's been my best season so far. It would have been a dream if I could have made it into the final, at least the semis.
"Going out in the heat was not on my agenda at all. I think that's why I am so disappointed, because I know I could be a finalist and it just wasn't there.
"I can run so much quicker. I think I'm in 1.58 shape so to run over two minutes is just a disaster in my opinion.
"I just have to try and get stronger and maybe have a few more races this year. I think I can be proud of what I've achieved so far and hopefully take that into next year."
As if making her debut in the big time was not enough, Judd's A-level results came out today.
"I don't want to know how I've done until I get home," she said.
"I think if they were bad results I think that would probably kill me right now, so I am just going to wait and get them next week and it'll maybe cheer my up a little bit."
Judd was one of three British hopefuls in the 800m this morning.
Marilyn Okoro produced a season-best performance of one minute 59.43 seconds to finish second and secure automatic qualification from her heat.
Laura Muir also impressed and a late surge down the back straight saw her through with a personal best time of 2mins 00.80secs.
"I'm just so shocked," Muir said. "I ran my own race as I knew it was going to go off pretty quick so I just thought I'd run my own race and I've got a strong finish so I could just use that.
"A personal best will have to be on the cards again for the next round."
Also in action this morning were Anyika Onuora and Jodie Williams, who both finished fourth in their 200m heats but with different outcomes.
Onuora looked set to finish in the top-three spot, but tailed off as the line approached to cross in 23.36s.
It soon became apparent that the time was not good enough for a fastest loser spot, unlike Williams.
Her 23.00s run saw her grab the final berth, meaning she will race again in this evening's semi-finals.
Elsewhere tonight, Perri Shakes-Drayton and Eilidh Child will be going a podium place the 400m hurdles.
Hannah England will hope for more 1,500m glory after taking silver two years ago, while Olympic bronze medallist Robbie Grabarz will look at add to his prize haul in the high jump final.