Popov started his career with local side Belasica and moved to Greece with Proodeftiki and AEK Athens.
He signed for Red Star Belgrade in 2004 but injuries prevented him from making an impact and he returned to Greek football with Egaleo after a short loan spell in Poland with Odra Wodzisław.
Egaleo were relegated in 2007 and Popov joined Levadiakos before moving to Dutch club Heerenveen in July 2008.
At Heerenveen he finally found some success and won the KNVB Cup in 2009 scoring in the final against FC Twente.
After good form in European competitions Popov signed for Ukrainian side Dynamo Kyiv. In August 2012, Popov signed for Stoke City on a season long loan deal, but the move fell through after he failed to be granted a UK work permit. However soon after a work permit was approved and he signed for West Bromwich Albion
He was then loaned out to West Bromwich Albion, though they are believed to be in favour of the player making a similar loan switch to Bolton.
According to the BEN:
Popov had travelled to the North West for a medical and was ready to end Dougie Freedman's long search for defensive cover, only for the Premier League and Football League to voice their concerns.
As the deal was agreed outside the regular transfer window, the authorities deemed it an international transfer rather than an emergency loan and so put the blocks on the move
Fingers crossed the deal goes through - because we're in dire need of reinforcements since the injury suffered by summer signing Marc Tierney.