College chiefs fear the introduction of tough new A-levels could "damage the education" of Birmingham teenagers.
As thousands of students across the city are set to find out their A-level results tomorrow, a new tougher style of A-level is set to be introduced in September.
Plans to reform the qualifications, making them purely exam driven and doing away with coursework, was announced two years ago by the previous Coalition Government.
The changes come into effect in the new academic year but critics claim it will spark "complications" and could harm students' education.
The reforms will see AS and A-levels no longer being connected so AS results will not count towards final grades.
Meanwhile, A-levels and AS qualifications will be marked purely through a final exam, with no course work or the opportunity previously enjoyed by students to re-sit exams in January.
There will also be more involvement from university lecturers in designing A-level content while there will be a reduction in the number of subjects available.
Education ministers believed the old A-levels were no longer preparing students for academic courses at university.
They also believed a structure where students were marked on coursework disrupted teaching.
There were also concerns about evidence of grade inflation which undermined the A-levels reputation as being the "gold standard".
Nick Davy, higher education policy manager at the Association of Colleges, said many felt this latest round of reforms was unnecessary and many universities were against the move.
"Cambridge University is opposed as it chooses future students partially on the basis of their AS results," he said.
"Colleges and schools with sixth forms are grappling with yet another reform that they didn't ask for.
"This will create significant time-tabling issues and could lead to some teachers teaching AS and A-level students in the same class but with both pre and post-reform curricula.
"Many are also concerned about the negative impact the reforms could have on students who struggle and need the support structure provided by the AS-level.
"During this transitional period, AS qualifications in the unreformed subjects will continue to be coupled with the A-level, so that marks gained at AS will count towards the A-level. This will not be true in the reformed subjects.
"It is as complicated as it sounds and will remain so until the reform process is completed. We don't know whether the new system will work better, only time will tell us that.
"But the reform must not be allowed to damage the education of Birmingham's young people and this is the most significant risk in introducing the new reformed A-level qualification."
Chris Keates, general secretary of Birmingham-based teaching union NASUWT, also expressed her concerns.
She added: "Our young people are working hard under tremendous pressure and, despite poorly planned reforms, constant criticism, cuts to pay and a rising tide of excessive bureaucracy and workload, teachers are continuing to deliver the best for pupils.
"Tomorrow's results will have been achieved despite the Government's reforms, not because of them."