Martins was attacked by a number of Sporting Lisbon fans before the Portuguese cup final and had decided to leave the club, along with a few teammates, citing safety reasons.
The deal is yet to be given international clearance but Atletico seem to have pulled off a coup, as a number of clubs were interested in the winger.
The 23-year-old played one World Cup match for Portugal but had a better campaign with Sporting, notching up 11 goals and providing 9 assists for the side.
Martins was linked with other Premier League clubs too. Tottenham and Chelsea and Arsenal had reportedly made a bid of £26million, which was rejected.
The Portuguese talent would have been a great addition to the side and would have been a quality cover for the likes of Mohamed Salah and Sadio Mane.
Martins might not have been a first-choice starter but given the number of games we would be playing this campaign, there is no doubt we could have used his quality in a few matches.
The 23-year-old can play on either wing and also as an attacking midfielder, so we could have used him in a number of positions.
However, our loss seems to be Atletico’s gain and the Spanish side have done really well in this transfer window so far, completing a move for Thomas Lemar and also keeping hold of star forward Antoine Griezmann.