Students from black and ethnic minority backgrounds have told ITV News they fear they will not be allowed to reach their full potential - if predicted grades are used instead of their final exams.
Studies show only one in six predicted A-Level results are correct - and experts fear that black and minority ethnic students will be hit hardest.
Research conducted in 2011 found black applicants had the lowest predicted grade accuracy - at 39% - while white students had the highest - at 53%.
Students across schools in Wales have been promised they will get fair grades based on teachers' predictions.
Tia Zakura-Camilleri was due to sit her GCSEs in the summer - and she told ITV News her past experience of predicted grades worries her.
"Last year I was predicted Bs and a C in my three sciences - and instead, I came out with all As."
"It scares me to be honest - everyone likes to think that the teacher will know you best and it can be fair, but at the same time I know some of the connotations with people from BME backgrounds.
Race equality charities fear that unconscious bias might play a part in the final grades.
"Our young people have been telling us that there are teachers who have a certain perception of them and their community and then the grades will follow to be negative", Ali Abdi from Race Council Cymru told ITV News.
The Welsh Government said teachers predictions will be double-checked.
In a press conference, the education minister said there is a "significant moderation process within Wales and outside of Wales to maintain the integrity of the system".
Kirsty Williams said the process will "give those students - who've had their education so badly disrupted - confidence in the grades that they're getting."
Mr Abdi added, "What's been put in place was without any consultation whatsoever of young people.
"These are extraordinary circumstances we find ourselves but we need to be having those conversations. There's an opportunity here to actually involve them."
Watch the report by Charanpreet Khaira: