The friendship that could decide this summer's transfer riddle

'We were introduced on the 3rd, when we travelled with the U16's. It was something instinctive. Because of our style of play, we started to look for each other and we connected very well. We had a lot of fun', a 15-year-old Coutinho told Spanish daily 'Marca' back in the day.

Neymar, today, spoke about the Spanish league, hinting about his future. 'It is the most spectacular and the best footballers are here', the, for now, Barcelona man said.

Their paths separated, but the friendship persisted. While Neymar remained in Brazil five more years, at Santos, Coutinho left Vasco da Gama to join Inter Milan.

He never managed to find his place in the Italian team and, a year and a half before Neymar travelled to the Catalan city, Coutinho was familiar with Barcelona thanks to his six-month loan spell at Espanyol.

In January 2013 he joined Liverpool, and in summer of the same year Neymar made a big-money move to Barcelona.

To date, the relationship between the two Brazilians continues to be one of sincere friendship. A friendship which could mark the current transfer window. Neymar wants Coutinho by his side.

In fact, Coutinho's signing could play a huge role for PSG and Barcelona in their respective attempts to attract or retain Neymar.

On the other hand, if Neymar finally joins the Parisian side, the Catalan team would do everything to bring in Coutinho as a substitute for the former Santos man.

Still many potential movements which could happen this summer, and one friendship which could prove decisive.