Morgan Whittaker says he did not refuse to play for Plymouth Argyle in their 5-0 loss to Burnley last week.
Pilgrims head coach Miron Muslic told the media the 24-year-old "did not show up" in time for the game and that he had been selected.
Whittaker left Home Park on Friday for Middlesbrough in a club-record sale worth £5m and up to £2m more in add-ons.
"I want to make it abundantly clear that I never refused to play against Burnley," Whittaker posted on Instagram., external
"It was agreed by myself and the manager that due to the bids on the table from both Burnley and Middlesbrough, I would not be up for selection.