A-level results are predicted to rise when they are announced this week, one of the country's foremost education experts has suggested.
And the number of boys achieving the very top grade could pull further ahead of girls due to an increase in take-up of maths - typically a high-scoring subject - according to Professor Alan Smithers, director of the Centre for Education and Employment Research at Buckingham University.
Last year, boys held a 0.9% lead over girls at A* grade, although girls had a 0.4% lead at A and A* grade combined - having out-performed boys every year since the millennium.
Entries to maths and further maths are up again, the former now replacing English as the subject with the highest intake - 85,980 entries compared with 78,800.
Since they award by far the most A* grades, this could lead to an increase in A* grades overall.
Prof Smithers said: "The grades have been narrowing since 2006.
"Boys tend to cluster in the subjects that give out a lot of the top grades, such as maths, Greek and Latin.
"Girls cluster in subjects like English that offer relatively few of the top grades, like English and psychology.
"It could be that boys go further ahead this year due to the increase in people taking maths and further maths."
His comments come just days before thousands of students across England, Wales and Northern Ireland learn their A-level results.
Last year, the proportion of A-levels scoring at least an A grade fell by 0.1 percentage points to 25.9%.
Official figures for 2015 showed that 8.2% of entrants received an A* grade, the same figure as the previous year.
The overall pass rate rose to 98.1% in 2015 - having fallen the previous year for the first time in three decades.
Prof Smithers said it was difficult to say what the pass rates would be this year, but that it was possible that the percentage of students getting the top grade could increase by one 10th of a per cent.
He said: "It's quite tricky to predict, of course, because the regulator Ofqual tries to keep the percentage of the grades awarded the same for year on year, bearing in mind the prior attainment (GCSE results) of the cohort.
"In 2015, interest in computing, RE, economics have gone up.
"The most A* and As go on further maths and maths. In English there are relatively few top grades and there entries have fallen by about 6%.
"These changes in entries could be overwritten by the other factors. The A* and A grades could go up just a bit, by a tenth of a percent or so."
This year's A-level results will be available to students on Thursday morning.