There were reports from 'Gazzetta dello Sport' on Sunday that the deal would be finalised the following day. However, sources in England on Monday have now claimed that the transfer will not be official until at least Tuesday.
This is because the 23-year-old will fly to the UK on that day to undergo a medical with Chelsea's team doctors after the two clubs have agreed a fee of £17.6million plus £7m in add-ons.
It would be a great end to the window for the Premier League champions who have been chasing the Brazilian since the start of January.
The month would be complete if Antonio Conte could secure a move for a striker too. However, it appears their quest for Edin Dzeko looks set to fall at the final hurdle due to the player's demand, with the signing of Arsenal's Olivier Giroud looking more feasible.