New Barcelona head coach Xavi believes Ousmane Dembele can be the best player in the world in his position and has urged the club to prioritize a new deal for the winger.

Dembele has failed to justify his transfer fee, reported at the time to be worth up to €147m with add-ons, since joining Barca from Borussia Dortmund in August 2017.

He has made 119 appearances for Barca in total, starting 76 of those. To put that into context, 10 players, three of whom left ahead of the 2020-21 season in Luis Suarez, Ivan Rakitic and Nelson Semedo, have featured more in that time, with Sergio Busquets (209) leading the way.

The France international returned from a five-month lay-off in last week's win against Dynamo Kiev, only to sustain a hamstring injury in that game that will again keep him out.

Despite Dembele's persistent fitness issues, however, Xavi made clear at his Camp Nou unveiling on Monday that he wants Barca to keep hold of the 24-year-old.

"He can be the best footballer in the world in his position," Xavi said at a news conference. "He has spectacular abilities and a winning mentality. His renewal is a priority right now.

"We have to work with him and demand a lot. That will also depend on him, on his mentality. He will have to train well to prevent injuries."

Dembele has scored 30 goals and assisted 20 more for Barca, meaning he has been directly involved in 0.65 goals per 90 minutes.

That is an identical return to highly regarded Liverpool pair Roberto Firmino and Sadio Mane, among players from Europe's top five leagues since August 2017.

However, it does lag considerably behind the likes of fellow forwards Erling Haaland (1.39), Lionel Messi (1.29), Robert Lewandowski (1.27), Kylian Mbappe (1.24) and Neymar (1.14) – the man he replaced at Camp Nou.

Dembele's existing deal is set to expire at the end of the season and he can therefore discuss ​a free transfer with other clubs from January 1.

Barca have numerous other issues to contend with between now and then, not least in terms of potential targets ahead of Xavi's first transfer window at the helm.

Asked if he is hopeful cash-strapped Barca can bring in new recruits, Xavi said: "We are going to assess it with the club and we are going to decide. 

"It is soon, but we are going to work to strengthen the team. It is always an opportunity. For me, it is clear that we must ensure all the players we have are clear about what they each have to do in every moment of a game."

Xavi's first game in charge of Barcelona, where he spent 17 seasons during his playing career, is against city rivals Espanyol on November 20.