The Denmark international moved to La Liga side Celta back in the summer of 2016 and has since gone on to make a total of 135 appearances in which he has netted 18 goals and contributed with 15 assists.
With Celta having had a miserable La Liga season last term, finishing 17th in the league standings, changes are expected to made this summer and Sisto could be one of many players to exit the Balaidos.
Galician journalist Victor Lopez has taken to Twitter to report that a transfer fee has now been agreed between Celta and Sisto's former club, whilst personal terms are next on the agenda.
O acordo entre o @RCCelta e o @fcmidtjylland para a venda de Pione Sisto é por 3 millóns de euros máis bonus por obxectivos. A última decisión será do futbolista dinamarqués que debe chegar a un acordo co club do seu país. Contámolo agora en @aocontraataque
— Víctor López (@victorsaians) August 5, 2020
Sisto, who has fallen out of favour over the last 12 months at Celta made the headlines in controversial fashion earlier this year after he broke quarantine rules and returned to Scandinavia, making his exit look extremely likely.
Celta's new arrivals this summer
The Galician club have already secured the signings of two players this summer.
Right winger Alvaro Vadillo arrived from La Liga rivals Granada on a free transfer whilst defensive midfielder Renato Tapia was signed on a similar deal from Dutch side Feyenoord.
Emre Mor, David Costas and Jozabed have all returned from loan spells away from the club.
Who has left the club?
Robert Mazan returned to Celta in June from his loan spell at CD Tenerife but he has now been allowed to leave the club on a free transfer.
The likes Jeison Murillo (Sampdoria), Filip Bradaric (Cagliari), Rafinha (FC Barcelona), Pape Cheikh (Lyon) and Fedor Smolov (Lokomotiv Moscow) have all left the club following the expiration of their loan deals.