Philippe Coutinho presented with a thigh injury during a medical with his new club Barcelona, which the Spanish side says will keep him sidelined for around for 20 days.
Coutinho was undergoing his routine medical tests with Barca on Monday morning as he put the finishing touches on his record-breaking move to the Nou Camp.
The Brazil international missed both of Liverpool's opening two games in 2018 with a thigh problem and Barca have confirmed he is now set to be sidelined for the rest of January.
A club statement read: "Coutinho has an injury to his right thigh and he is expected to be out for around three weeks."
Coutinho was due to sign a five-and-a-half-year contract with the Catalan giants following his medical before being officially presented this afternoon.
The switch will see Coutinho become the second most expensive footballer in history after Liverpool and Barca agreed a deal for the playmaker which could be worth up to £142million.
It is the biggest transfer fee involving a British club and is also the most Barca have ever paid for a player, eclipsing the £96.8million - rising to a possible £135.5million - they splashed out on Borussia Dortmund winger Ousmane Dembele last August.
Coutinho's compatriot Neymar is the world's costliest player following his £200.6million switch from Barca to Paris St Germain.
Barca have had to bide their time to secure Coutinho's services, having seen a £118million bid rejected by Liverpool in August after making him their number one target to replace Neymar.
Coutinho also handed in a transfer request at the time in an attempt to force a move, but was unsuccessful.
Barca maintained their interest in the former Inter Milan man, though, and on Saturday the clubs announced a deal had been struck.
If Coutinho, who spent six months on loan at Barca's city rivals Espanyol from Inter in 2012, is unavailable for the remainder of the month then he would miss at least four LaLiga and Copa del Rey games for his new employers.
Barca's first match of February is scheduled to be the derby against Espanyol.
It's only eight days into the January transfer window and already we have the second biggest transfer ever about to be formally completed as Philippe Coutinho completes his Barcelona medical at the Nou Camp.
What a couple of months it's been for Liverpool Football Club. At the weekend they sold Philippe Coutinho to Barcelona for £142 million (€160m). Last week they bought Virgil Van Dijk from Southampton for £75m (€85m). And in November they agreed to pay their stadium staff the £8.45 (€9.53) an hour recommended by the Real Living Wage campaign, a whopping 95p (€1.07) increase. They'll start in June.
Real Madrid players feel like their La Liga title hopes are "sinking" into a black hole after they let a 2-1 lead against Celta Vigo slip through their fingers in the final eight minutes, leaving them 16 points adrift of leaders Barcelona.