Multiple reliable reports are claiming that Barcelona are keeping tabs on Nathaniel Brown, who plies his trade as a defender for Frankfurt. The move is still in the early stages, but interest appears to be growing. Barcelona have laid out their intentions, but valuation and timing remain under debate. Real Madrid, Man Utd and Arsenal are keeping tabs in case talks collapse or progress slows further. Barcelona's back line has been a real strength this season, conceding just 1.14 goals per game (16 in 14). Nathaniel Brown would be expected to slot into that unit and hold his own in an already solid setup. Frankfurt have also been linked with Jorthy Mokio while Barcelona are reportedly monitoring Pedro Neto, Sehrou Guirassy and Julian Alvarez. Stay tuned for more details as the story develops. Need more Barcelona transfer rumours? Follow @PlayerSwitchCom on Twitter for news and updates as they happen.