The doctor caught up in the Harlequins fake blood controversy admitted on Monday she had cut the lip of the player at the centre of the scandal.
Harlequins wing Tom Williams had earlier bit into a fake-blood capsule to engineer a blood replacement which allowed a substituted specialist kicker back on to the field in the closing minutes of their European Cup tie against Irish province Leinster in April last year.
As it was, Irish province Leinster won 6-5.
Williams told a medical disciplinary hearing in Manchester on Monday he had to twice ask the club's matchday doctor to make the incision in the treatment room as he became "extremely panicked" when match officials questioned whether his injury was genuine.
Dr. Wendy Chapman, 46, could, if found guilty, be struck-off in a move that would all but end her medical career.
At the start of a hearing expected to last two weeks, Chapman admitted she cut the lip with a stitch cutter and she did so because Williams wanted to demonstrate a "real injury".
Michael Hayton, opening the case for the GMC, stressed Chapman had not been involved in Williams's original act of cheating.
"He had been sent on to the field of play and had bitten into a theatrical blood capsule, of a type used in amateur dramatics, to imitate blood," Hayton said. "This was cheating to get the best kicker back on to the field.
"Tom Williams played a part in it. Dean Richards (Harlequins director of rugby) played a part in it. Dr Wendy Chapman did not.
"It is not the case of the General Medical Council that she was party to the planning and the carrying out of the cheating.
"She had no knowledge or active participation in it."
Hayton said the issue concerning Chapman happened when Williams came off for treatment.
"When Tom Williams came off it was apparent to a number of people that what was coming from his mouth was not blood and it led to disquiet from Leinster officials, as they saw it was a ruse to bring back on Nick Evans.
"There was no doubt that the atmosphere was highly charged.
"What then took place is that the doctor examined Tom Williams and said he had a loose tooth in the presence of others.
"Then at the request of the player she cut his lip with a stitch cutter to cause an injury. Dr Chapman has admitted the purpose was to justify his replacement."
Williams was provided with the blood capsule by Harlequins physiotherapist Steph Brennan, on Richards's instructions.
Former England No 8 Richards was given a three-year ban by the ERC disciplinary panel after it emerged he had faked blood injuries on several occasions, while the club were fined 259,000 pounds.
Williams had a one-year suspension reduced to four months on appeal after providing the hearing with new evidence, which exposed an alleged cover-up.
Chapman, an accident and emergency consultant at Maidstone Hospital in Kent, is currently suspended from practice, pending the outcome of the GMC hearing.
Source: AFP European Edition