The Paris Saint-Germain icon has been criticised for appearing to snub Ralston after the final whistle, refusing to give his shirt to the 18-year-old.
However, Sportsmail can reveal the reason Neymar declined to give his shirt to the teenager is because he had already committed the jersey to the Marina Dalglish Appeal.
The charity – set up by the Dalglish family in 2005 – focuses on helping those diagnosed with breast cancer.
Celtic and Liverpool legend Kenny Dalglish played an integral role in establishing the charity with wife Marina. The shirt will be used to raise money at a forthcoming event.
Neymar, the most expensive player in football history, and Ralston were involved in a heated confrontation during PSG’s 5-0 win at Parkhead on Tuesday night, the Celtic defender laughing in the Brazilian’s face at one point.
The former Barcelona man had been accused of not handing over his top to Ralston because of the clash.
But the South American was merely sticking to his agreement with the charity.