Great Britain's Olympic champion Jade Jones missed out on a medal at the World Championships after defeat by Mayu Hamada in -57kg quarter-finals.
European champion Michael Harvey also exited at the same stage, which followed defeats for Lutalo Muhammad and Martin Stamper earlier in the week.
Jones, 20, fought back from 2-0 down to draw 2-2 with Japan's Hamada, but then lost to a sudden-death golden point.
"I'm devastated and so is the team," said Jones.
"I'm only 20 I've still got ten more years to become a multiple world champion but I'm just gutted at being one point away from a medal."
The fighter from Flint in Wales, who won silver at the event two years ago in South Korea, had looked impressive earlier in the day seeing of the challenges posed by Iran's Sousan Hajipourgoli and Martina Zubcic of Croatia.
Hopes were high that Jones could end Britain's medal drought in Mexico as she had defeated Hamada 13-3 en-route to Olympic glory last summer.
Jones was denied a crucial three points for a head-kick in the second round, but generally struggled to make an impact.
"I thought it definitely scored but that's just how taekwondo is," reflected Jones.
"I didn't start how I should have and then came back too late and obviously golden point is always 50-50.
"At the end of the day it's my own fault and I should have been better from the start."
Under-63kg European champion Harvey, who also claimed World silver in 2011, surrendered a 4-3 lead with one second remaining to lose 7-4 to Frenchman Stevens Barclais.
"I was in a difficult situation," reflected the British fighter.
"I couldn't go defensive and be penalised and I had to try and stop him scoring but he got me in the neck and I'm just gutted."
The results on day six of the competition mean that Great Britain - who were targeting one to three medals - have achieved just three quarter-final places so far.
Harvey though denied that the poor results by his team-mates had influenced his performances.
"It's an individual sport in one sense but in the other you have to keep pushing for the other players and make sure that we don't make a negative vibe," he said.
"Everyone's been really positive even though they've lost out."
Great Britain have one final chance to hit their minimum medal target in the form of two-time open championship winner Damon Sansum who competes in the -80kg division on Sunday.
European Champion Aaron Cook, who was controversially overlooked for last summer's Olympic squad, will also fight in that category but represents the Isle of Man.