Borussia Dortmund star Marc Bartra has warned Barcelona fans against making comparisons between the "great" Ousmane Dembele and Neymar.

The La Liga giants were already interested in Dembele during the last summer transfer window before the France starlet decided to join Dortmund from Rennes. The club thus decided to revive their interest last month after losing Neymar to PSG in a €222m world-record transfer.

Dortmund were reluctant to part ways with the Frenchman after he enjoyed a fine debut season in the Bundesliga, scoring 10 goals and grabbing 21 assists in 49 appearances.

However, Barcelona managed to convince them to cash in after agreeing to make him the second most expensive player in history in a deal worth €105m (£97.6m, $125m) plus €40m in add-ons.

Dembele has thus been tipped to fill the huge gap left by Neymar in Ernesto Valverde's attack - with the other four signings made to the date being low profile additions such as Paulinho, Nelson Semedo, Gerard Deulofeu and Marlon Santos.

Bartra, who made made the opposite move from Barcelona to Dortmund two years ago, has backed Dembele to be a long-term success at his former club, but he warned against expecting too much, too soon for the 20-year-old winger.

"He is pure talent. It'sa great signing [for Barcelona]. I've played with him this year and he's a great player but you have to be patient; he's very young and he's just starting," Bartra said in a press conference while on international duty with Spain.

"You can't compare him to anyone else; at the end of the day Neymar is among the top three players in the world. You have to be patient. He's one hell of a player and will be real entertaining. He causes teams lots problems and at the end of the day I guess that this is what Barcelona were looking for with his signing."

Meanwhile, Barcelona have confirmed that the French starlet completed his first training session with the club on Tuesday (29 August) as the players who are not on international duty continue the preparations for the upcoming derby against Espanyol on 9 September.

Furthermore, the club revealed that Marlon Santos missed the workout after being granted permission to negotiate a loan move to OGC Nice.

"Marlon Santos was missing with special permission from the club, which is sorting out negotiations for his loan to French outfit Nice," Barcelona confirmed in the club website.

The Brazilian defender only joined Barcelona this summer after the Catalans activated an option to secure his services from Fluminense, having impressed on loan with the second team during the 2016-2017 campaign. However, Valverde last week suggested that he could be loaned out to continue his development.

Bartra played alongside Dembele at Dortmund during the last season. Getty