Moussa Dembele claims Celtic "gave in" to sanction his £19.7m late deadline day move to Lyon.
The French striker signed a five-year deal on Friday night, 24 hours after sitting out the club's Europa League win over Suduva.
Manager Brendan Rodgers said in a statement the transfer was "to serve the best interests" of "the culture and environment" at Celtic.
"I was determined to come to Lyon," Dembele said at his unveiling.
"Those in charge gave in. It was hard. I gave everything and in the end, it paid off."
On Thursday Dembele, who signed for Celtic from Fulham in 2016, tweeted "A man, without his word, is nothing. A real man keeps his word", and "A lie has many variations, the truth has none".
The following day he briefly took part in training before going back into the club's Lennoxtown training ground hours before his transfer was confirmed.
Celtic signed midfielder Youssouf Mulumbu and brought in defender Filip Benkovic on loan on Friday, but did not bring in a replacement striker after Dembele's exit.
"It was a certainty that I wanted to come to OL," added the Frenchman.
"I have played with a lot of Lyonnais players. They all told me to come. I'm a scorer, it's my first quality.
"Celtic needed a replacement to finalise."
The Ligue 1 club's president Jean-Michel Aulas said Dembele's determination to move to Lyon made the transfer happen.
"Without that, he could not have come," he explained.
"The club has a financial strength that is recognized throughout Europe. Sometimes you have to use it."
Former Celtic striker & BSports Scotland pundit Scott McDonald
It's an amazing amount of money. But they've lost, I believe, their best striker at this moment in time and haven't found a replacement.
To even be thinking about turning it down just shows you what Celtic's position is financially. But Celtic fans won't thank you for that right now.
There will be people concerned at the moment about whether they can go with two strikers up until January.
I'm hugely surprised. Everything that came out yesterday and the day before was that he wasn't going to be sold.
If the cryptic tweets were anything to go by then there certainly has been a fall-out.