Changes are being considered to the way A-level grades are awarded in Wales, the day before they are published.
Ministers have been in discussion with exam regulators after major announcements about the grading system in other parts of the UK.
Pupils in England are being told their final results will be no lower than their mock exams.
Welsh ministers say they want to make sure students in Wales are not disadvantaged.
More details are expected later on Wednesday.
The Scottish government announced on Tuesday that all pupils would get the grades predicted by teachers.
The Welsh examinations board, the WJEC, said it was “awaiting further details from government departments and the qualifications regulators”.
This year’s exams were cancelled across the UK because of coronavirus, with governments of the UK having to find alternative ways to assess pupils’ performance this year.
In Scotland 76,000 pupils in had their results upgraded after being lowered by a moderating system which critics claimed was a “postcode lottery” as it linked pupils’ results with their schools’ past performances.
Now, the Department for Education in England has announced a “triple lock” – so results will be the highest out of their estimated grades, their mocks and an optional written exam in the autumn.
Sally Holland, the children’s commissioner for Wales, said she wanted to see the Welsh Government “assuring students today that they will not be put at a disadvantage as a result of last minute changes by the Scottish and UK governments”.
“I would also be expecting Welsh Government to be discussing with universities and others to ensure no student from Wales will be placed at a disadvantage in admissions processes.”
Plaid Cymru has called for a free and independent appeals process to be available to all A-level students in Wales getting their results on Thursday.
The party’s education spokeswoman Sian Gwenllian said Wales’ Education Minister Kirsty Williams may want to consider making the same changes as England “if after Thursday it becomes apparent that lots of young people are being let down by the system”.
Suzy Davies, who speaks for the Welsh Conservatives on education, said Wales and England were in a better position than Scotland on the matter.
“Welsh pupils are having their AS grades taken into account as part of their assessment, which would have been earned through formal examination last year.
“In England, where there is no such data, mock results are just one criterion in assessment and seem to be acting as a floor rather than a ceiling in their assessment system.
“Neither nation is in the sad predicament we see in Scotland.”
A Welsh Government spokesperson said: “We are monitoring the situation across the UK and are in discussions with exam regulators to ensure decisions taken in other nations will not adversely impact students in Wales who are awaiting their results tomorrow.
“A-level grades in Wales will reflect work that has been completed by the students, as AS-levels continue to count towards final A-level grades here.
“In addition, a national model has been developed by WJEC and approved by Qualifications Wales to ensure that learners this year are not disadvantaged and will be able to progress with confidence.”
“While there are similarities in the models used across the UK, in Wales we have been able to use a greater range of prior attainment data, including AS-levels, GCSEs, GCSE units and Key Stage 3 teacher assessment and national test data, to improve accuracy.”
The WJEC said: “We are awaiting further details from government departments and the qualifications regulators.
“Once we have more information to share, we will make it available on our website.”
In a statement, Qualifications Wales said it was “aware of the emerging changes in England and are working with Welsh Government to establish the impact of these decisions on the approach adopted in Wales”.
“In the meantime, we are confident that the approach to standardisation that we have adopted is overall the fairest option in the circumstances.”
On Tuesday, Welsh Housing and Local Government Minister Julie James insisted that Wales used different modelling to Scotland and that nearly half of pupils’ final mark was based on AS-levels completed last year.
Ms James said she was confident pupils’ grades would be “robust” due to the system used by the examination board WJEC and exam regulator Qualifications Wales.