Barcelona had announced that Miralem Pjanic had tested positive for coronavirus after feeling "a little unwell", adding that he was in "good health" and self-isolating at home.
Barcelona have demanded that Arthur Melo returns to training as he is under contract till the end of the season.
The two deals have gone through separately, allowing both clubs to boost their profit figures ahead of the end of the financial year on June 30.
Amid reports of Arthur's move to Juventus, Barcelona manager Quique Setien said that he is counting on the 23-year-old midfielder to play a part in their next La Liga game against Celta Vigo.
Maurizio Sarri said he spoke to Cristiano Ronaldo and told him not to worry about his form.
Juventus have started training on an individual basis, complying with the regulations set by the government.
Juventus' win over Napoli stretched their lead at the top of the Serie A to a huge 16 points.
A tearful Cristiano Ronaldo left the pitch in disbelief in the 29th minute, having aimed a petulant, but seemingly harmless, kick at Valencia defender Jeison Murillo.
Napoli, under the watchful eyes of former star Diego Maradona, now trail Rudi Garcia's early season pacesetters by five points.