Liverpool are understood to have promised Philippe Coutinho that they will "facilitate" his departure to Barcelona during the upcoming January transfer window if the La Liga giants return with a reasonable offer.

Mundo Deportivo claims that the two parties reached an agreement in the summer in which the Merseysiders vowed that they will negotiate Coutinho's transfer to Barcelona if the player didn't refuse to play the Champions League for Jurgen Klopp's side during the first part of the season.

Coutinho only signed a new deal, reportedly worth around £150,000-a-week, in January to become the highest-paid player at Liverpool.

However, the 25-year-old playmaker tried to force a move to Barcelona during the summer with the La Liga giants submitting multiple offers for the Brazil international.

The Catalans were eventually forced to abandon the pursuit on deadline day after Liverpool asked them to pay €200m (£179.3m, $236.8m) to complete the deal.

Barcelona president Josep Maria Bartomeu recently suggested that the club would not make a new attempt to sign him in January due to the Reds' high demands.

"Right now there is nothing planned for the January window. [Technical secretary] Robert Fernandez, [sporting football manager] Pep Segura and their team will work to see if they believe it is necessary to do something," Bartomeu said when to TVE when asked if Barcelona will make a new attempt to sign the Liverpool star ahead of the second part of the season.

"I will not say how much we offered, but they asked for €200m. We weren't going to give €200m or €150m – we decided to step away from such an expensive market, our offer was less than €100m, with add-ons it could have reached €120m."

However, several reports in Spain are claiming that the La Liga giants do plan to revive the pursuit in January as manager Ernesto Valverde is still keen on adding the Brazilian ace to his ranks.

Last week, Mundo Deportivo reported that Barcelona hoped Liverpool will soften their stance with the club hopeful of complete a deal for the same €80m (£71.6m, $94.5m) plus €30m in add-ons package which the Merseysiders rejected in the summer.

Now the Spanish publication claims that Coutinho has "an ace up his sleeve" to make that move due to an agreement he reached with Liverpool in which the Anfield club promised to let him go if Barcelona make an acceptable offer.

Mundo Deportivo says that Coutinho was ready to go on strike and not play again for Liverpool after the Premier League side blocked his desired move to Barcelona in the summer.

However, the player finally agreed to play in the Champions League for Liverpool during the first part of the season after they promised to negotiate his exit in January.

Coutinho has already fulfilled his part of the deal after he feature in the first two Champions League games of the campaign against Sevilla and Spartak Moscow, scoring against the Russian club in a 1-1 draw.

Coutinho would be cup-tied for Champions League games should he move to Barca but that is not expected to affect the move.

Manager Ernesto Valverde believes that Coutinho could provide a big boost to his side in the fight for the La Liga title and the Copa del Rey, allowing him deploy a fresh Andres Iniesta in the Champions League.

Furthermore, Barcelona are determined to advance his arrival to January in order to avoid Paris Saint-Germain joining the race next summer.

Philippe Coutinho
Coutinho has been in superb form since returning to the Liverpool fold after a summer of uncertainty. Getty