Barcelona have already approved the deal.
Italian journalist Fabrizio Romano confirms that Hector Bellerin has just left Barcelona and landed in Lisbon:
"Hector Bellerín landed in Lisbon with his agent and on his way to the medical tests as new Sporting player."
"Barcelona have already approved the deal."
Bellerin has only played seven times for Barca, three in La Liga, two in the UCL and two in the cup. He has been on the bench eight times in a row in the league. In the Spanish Super Cup he was one of the discarded players.
The player has been mostly frozen out and has the green light to leave Barcelona.