Atletico Madrid were eliminated from Europe in midweek after a 2-1 loss at Porto and are looking to bolster their squad.
One player who could be sold is Joao Felix, who Atleti signed for €126m from Benfica on a seven-year deal in 2019.
The Portuguese forward has been underrated this season, with just two goals and has been inconsistent at times.
Cadena SER claim that Atletico Madrid have put Joao Felix on the market and are open to offers for him.
Bayern Munich were rumored to have made a €100 million off-season move for Felix, while Manchester United reportedly rejected a €130 million bid in August.
Fichajes reported last month that the 22-year-old had handed in a transfer request, while Paris Saint-Germain and Barcelona had recently been linked with him.