Barcelona manager Xavi Hernandez said "the doors are open" for Lionel Messi to return to the club.
Xavi was speaking on the eve of Sunday's clasico, when Barca face La Liga leaders Real Madrid at the Santiago Bernabeu.
Messi has endured a disappointing season at Paris Saint-Germain, although Barca's desperate financial situation would make re-signing the Argentinian difficult.
La Liga's latest spending restrictions published last week set Barcelona's limit at $159 million. It means the club will have to make considerable savings to sign anyone in the next transfer window.
Messi was let go last year because Barca could not afford to renew his contract, bringing an emotional end to the striker's historic career at Camp Nou.
Asked if he would open the door to Messi coming back, Xavi said: "He is the best player in history and the history of the club, he's earned the right to have the doors open to him.
"As long as I am coach the doors are open to him if he wants to come any day. He is the best in history and as a club we owe him a great tribute, he deserves it, but he has a contract with PSG, so there is little more I can tell you.
"If he wants to come any day, to see training, talk to the coach, the doors are open because he is the best player in the history of the club."
Without Messi, Barcelona struggled for much of the season but Xavi, who was appointed in November, has overseen a significant upturn in form.
Barca sit third, on course to qualify for next season's Champions League, and will be hopeful of landing a confidence-boosting victory against Real, who will be without their star striker Karim Benzema.
Benzema is out with a calf injury and will not be risked, allowing the Frenchman the international break to recover for the run-in and Champions League quarter-finals against Chelsea.
"Tomorrow he can't play because he hasn't trained," said Carlo Ancelotti on Saturday. "He still feels a little discomfort, it's a small injury, but it won't let him train and obviously he won't play either.
"The fact that he doesn't play doesn't worry me because it means we will have two weeks to get him ready for the end of the season when he will be very important as always."
Despite winning their last four consecutive league games, Barcelona are 15 points behind Real in the table, although they have a game in hand.