Sunderland Football Club is being pressed to explain when it knew the full extent of Adam Johnson's sexual activity with a 15-year-old fan.
The England winger was convicted on Wednesday of sexual activity with the girl after admitting he groomed her.
The club should explain why Johnson was allowed to continue playing after he was charged, a women's charity said.
At a press conference manager Sam Allardyce said he was shocked and that Johnson had "let everybody down".
"My position was just what I'd heard from Adam," he told the media on Thursday. "But him changing his plea was a shock, while with the end verdict you can have nothing but sympathy for the victim."
In a previous statement, the club said had it known 28-year-old Johnson had planned to plead guilty he would have been sacked immediately.
'Vilified by strangers'
However, during the trial, the jury was told that, before the case came to court, club bosses had seen all the 834 WhatsApp messages the pair sent to each other, along with transcripts of police interviews.
Clare Phillipson, director of charity Wearside Women in Need, said by allowing Johnson to continue playing Sunderland had made "tens of thousands of fans and lots of other people" think he was probably innocent, leaving the teenager "vilified and not believed".
"They have given a statement but I think there are questions that are just not answered in that statement, around what Johnson said in court, about what they knew and when.
"We need to consider the impact on this child of somebody, week after week, being cheered and supported while, at the same time, on social media she was being vilified by thousands of complete strangers to her."
The club has been approached for clarification on who knew what, when, and why it lifted Johnson's suspension.
Johnson was cleared of one charge of sexual activity with a child but warned he faces a "substantial prison sentence".
Ms Phillipson said Johnson had access to the girl, a Sunderland fan, as a "direct result" of working for the club and of her "idolising him as a high profile player of her club".
It was not a case of when the club knew he was going to plead guilty, but when it knew he had met her, exchanged messages and been alone with her in a car, she said.
Johnson was suspended on his arrest but this was lifted two weeks later after the football club took legal advice and carried out a safeguarding assessment, Sunderland's statement said.
Claims that the club was involved in "tactical discussions about his plea" to allow him to continue to play were "utterly without foundation" and "refuted in the strongest possible terms", the Premier League club said.
It would not be commenting further, it said.
John Cameron from the NSPCC said it "beggars belief" that Sunderland did not maintain the suspension of Johnson until the case was resolved at court.
He told BBC News: "Up and down the country there are a number of organisations where professionals work with children and, where allegations are made, it is standard practice for people to be suspended until matters are concluded.
"Here we have a young girl who had the courage to come forward, a serious victim of extensive grooming by someone who completely used their celebrity status for his own sexual gratification.
"What does this really say to a victim when they see a player like this coming out and getting support from the club? Well it clearly gives a strong message that there is significant doubt in this club's mind."
Mr Cameron also said footballers had a "responsibility" to ensure they conduct themselves "appropriately" and, if they used their position to abuse others they would be held to account.