According to talkSPORT, the mystery man in this Instagram photo taken by West Ham striker Diafra Sakho is former Hamburg winger Josef Shirdel - and the youngster could join the Hammers after a trial period.
The Hammers have won just one of their last 11 games, and even with the future of manager Sam Allardyce in doubt, it seems that the club are still looking at possible additions to the squad.
West Ham are currently away in Dubai for warm weather training, and fans were fascinated when striker Sakho posted the aforementioned photo alongside a mystery team mate.
Fans now appear to know who the player is, with talkSPORT revealing it's former Hamburg winger Josef Shirdel, with the German currently on trial with the Hammers.
Shirdel, 21, has been a free agent since the end of last season when his Hamburg contract expired, having failed to make even one appearance for the Bundesliga side.
Primarily a right winger, Shirdel has been hoping to impress Allardyce enough to earn a permanent contract at Upton Park - and may well have done it.
talkSPORT are today reporting that West Ham are mulling over a deal for Shirdel, and because he's a free agent, they don't need to wait until the summer transfer window opens to sign him.
He's far from a household name and unlikely to make a huge impact on the first team should he sign immediately, but it seems that Shirdel has impressed enough to make West Ham consider him long-term.