Record numbers of students began fighting for the last remaining university places today as the A-level pass rate rose for the 29th year in a row.
One in 12 (8.2%) entries received an A* grade this summer, but the number of exams scoring at least an A plateaued for the first time in 15 years.
More than one in four (27%) exams achieved at least an A, the same percentage as in 2010. The last time this percentage stalled was in 1996 and 1997, when 15.7% of exams were awarded at least an A.
More than 250,000 teenagers in England, Wales and Northern Ireland received their long-awaited A-level results today with the the overall A*-E pass rising to 97.8%.
National figures published by the Joint Council for Qualifications (JCQ) show that boys have closed the gap with girls on A* grades.
Some 8.2% of boys' entries achieved an A* this year, up from 7.9% in 2010. Girls' performance dipped slightly, with 8.2% of girls' entries awarded the top grade, down from 8.3%.
Andrew Hall, chief executive of the AQA exam board, said: "The sense I have, and it's a personal opinion, is that boys, I think, are recognising that the challenge is there."
Education commentators have suggested the creation of the A* has provided a challenge that boys have risen to, Mr Hall said.
But while many teenagers will be celebrating tonight, others still face a desperate scramble to secure a university place.
Students who miss out this year will have to apply again next year - and have to pay £9,000 in annual tuition fees.
Latest figures show that 682,367 people have applied to start undergraduate university courses this autumn; of these 57.6% have been accepted so far.
And as of 12.30pm today there were 189,992 students eligible for clearing, compared with 185,223 at the same time last year.
Last year, almost 47,000 people found a place through clearing.
Union leaders have warned that young people are being "badly let down" by the Government.
The rush for clearing places was exacerbated earlier today by a fourfold increase in the number of visits to the Ucas website, which forced the site to close temporarily.
Tens of thousands of students were left in limbo when Ucas closed the site at 8.40am due to unprecedented demand.
Ucas insisted that the closure would not affect students' ability to choose a clearing place, and the site was back online shortly before noon.
"Obviously, for Ucas, any service failure is something that we don't want to happen," chief executive Mary Curnock Cook said.
"We are here to try and provide advice and services to our applicants and to our member universities and colleges, so any disruption in service is not how we would wish it to be."
Tom Spencer, 18, from Ely, Cambridgeshire, was one of those who faced problems accessing the site this morning.
He eventually found out he had won a place to study environmental sciences at Manchester University after a letter from Ucas arrived through the post.
He called on Ucas to ensure they are able to deal with the volume of traffic to their website.
"They need to make sure they can handle the numbers, they should know how many people are going to be trying to get on at this time."
Today's results showed a continuing resurgence of science subjects and mathematics.
Biology entries were up by 7.2%, with chemistry up 9.2%, physics up 6.1% and mathematics, including further mathematics, up by 7.4%.
Traditional modern languages continue to decline, with the numbers for French going down by 4.7% and those for German decreasing by 6.9%.
Dr Wendy Piatt, director-general of the Russell Group of leading research universities, said it was "encouraging" to see a rise in the numbers of students taking science and maths.
But she added: "We remain concerned that too few students from some state schools take or get the top grades in science, maths and language A-levels, restricting their options at university and closing off certain career paths."
Union leaders said a lack of university places, funding cuts and the promise of £9,000 tuition fees are creating mounting problems for youngsters.
TUC deputy general secretary Frances O'Grady said: "Because of the rush to avoid next year's fees hike, and the Government's refusal to fund extra university places, record numbers of students will lose out on higher education altogether."
She added: "Young people are being badly let down by this Government - a failure that carries a devastating social and economic impact."
Unison general secretary Dave Prentis said: "Students should be celebrating their results and planning their futures. Instead they are hit with huge tuition fees, rising unemployment and drastic career service cuts.
"These students have come to a major crossroads, yet have no skilled help in choosing a route. If they feel that options are blocked off to them it will create a lost generation of young people."
Schools Minister Nick Gibb said: "We want students to leave school with the skills to lead a successful and fulfilled life. Students have done their part by working conscientiously and taking the exams put in front of them.
"But now we in Government have to do our part to make sure our qualifications match the best in the world and keep pace with the demands of employers and universities."