England's biggest school exam board is introducing a new top grade - an "A* with distinction" - for the very highest performers.
AQA has brought in the grade, which trumps even an A* for its new IGCSE in further maths, The TES has learned.
The board has "no plans at present" to extend the grade to other qualifications and subjects, but academics say it is likely to become a trend and a pre-requisite for elite universities, making the standard A* look second best.
The new grade will be awarded to pupils who show "sustained mastery" of the "most challenging aspects" of maths from next year.
AQA chief executive Andrew Hall said: "We believe the most able mathematicians who are already likely to achieve A or A* at GCSE will be motivated by the added challenge of mastering the most demanding skills and being rewarded for this."
His board says there is a genuine need for the A* with distinction grade in a subject with a wide spread of ability and a qualification aimed at a high-achieving minority.
The ever-increasing proportions of candidates gaining top grades in all subjects means many have seen the replacement of the A* - introduced in 1994 for GCSEs - with a new top grade as only a matter of time.
The A* was introduced to A-levels last year and was immediately achieved in 8 per cent of entries, the same proportion that gained an A grade when it was first used in 1965.
Professor Alan Smithers from Buckingham University said: "Exams tend to be a case of follow my leader. I am quite sure that young people not taking further maths might want to get an A* with distinction. So it could start a trend.
"In effect you will be turning the A* into a kind of failure. You might be setting an impossible standard at the top."
AQA's further maths IGCSE aims to stretch "really top performers" in preparation for A-level and includes additional algebra, geometry, proof and calculus.
Mr Hall said: "Where students can show sustained mastery of these, it is appropriate to recognise this with a further grade beyond A*."
Last year saw 5 per cent of maths GCSE entries gain an A* and 11 per cent of entries in additional maths.
The A* with distinction will be based on a judgment on which candidates demonstrate "sustained performance" in higher-order skills such as reasoning and problem-solving alongside "exceptional technical proficiency". It will not be awarded to all candidates achieving a fixed percentage of marks.
Cambridge University senior research associate John Bangs said: "Once one exam board does this the others will follow.
"This will become a prerequisite for Russell Group universities which look for these new distinctions as an easy way out of taking a 360-degree view of students."
The further maths exam is part of a new suite of IGCSEs developed by AQA for teaching from September. It has already been approved by exams watchdog Ofqual, alongside two English IGCSEs. A new science IGCSE is still going through the process.
Original headline: `A* with distinction' could become the norm for the best of the best