BLUES centre-back Leon Johnson said 'silly mistakes' cost Wycombe yet again at Charlton on Saturday.
A defensive error saw right-back Marvin McCoy robbed of possession to allow the Addicks to undo all of Wanderers' good work and snatch a win to claim the League One title.
"We tried hard and worked hard but silly mistakes have cost us again," said Johnson. "We can take heart from performance and still have two games to go but it is a very disappointed changing room.
"Everyone is hurting. I am sure we will pick ourselves up during the week and get ready for Notts County. If it was a brilliant bit of play that undone us then you can hold your hands up but from a silly mistake it has cost us. It is not just today it has been like that through the course of the season."
Defeat leaves Wycombe three points adrift of Walsall ahead of their final home game of the season against Notts County on Saturday.
"We will keep going until the end," added Johnson. "If we win next weekend, it can all change again."