Zigic was part of Serbia's squad in South Africa but will link up with his new team-mates next Monday in time for Blues' pre-season tour of Hong Kong and China beginning on July 14th.
Blues boss Alex McLeish, who splashed out £6million on Zigic, said: "He certainly didn't play as many games as the lads in our squad last season when, for a long time, we fielded virtually an unchanged team.
"He should be fine and in any case we've got to get him up to a level of fitness where he's ready for the Premier League."
McLeish, who has also signed goalkeeper Ben Foster from Manchester United for £6million, added: "We will be showing Nikola some of the footage from last season which should give him a good insight into what he should expect.
"The Premier League is rough, tough and, while Nikola is a big lad, the Premier League is hard in terms of aggression and that different style of football."
McLeish is adopting his normal stance of not discussing potential transfer targets but it is understood Marseille's Ghana winger Andre Ayew, who impressed during his country's run to the quarter-finals, is on his radar.
Source: PA
Source: PA