Manager Neil Lennon did not fly into the Costa Del Sol with the travelling party, but is expected to arrive over the next 48 hours.
His latest signing, Israeli defender Rami Gershon, is preparing to join his new team-mates after the club confirmed his loan transfer from Standard Liege.
Australian rising star, 20 year-old attacking midfielder Tom Rogic, is another en route to Marbella to begin training with Scott Brown, Gary Hooper, Victor Wanyama and Co.
The Central Coast Mariners kid is serving a domestic suspension, and his A League club have given him permission to accept the invitation to hook up with the Hoops.
Rogic's contract will run out in May, sparking interest from around the globe.
While Celtic have yet to indicate if they are considering making an offer for him, if they do try to sign him, he will require a work permit.
That has been a problem in the previous attempts to lure Rogic to Britain. His proposed move to Reading last year fell down due to this.
But since then Rogic has become a full international, and this would be important if Celtic did decide to try and recruit him.
The completion of the necessary work permit is also a factor in why Gershon has not yet joined up with the SPL champions.
But Celtic anticipate this can be resolved soon and that the established internationalist – whose initial deal is until the end of the season with the Parkhead club holding an option to make it permanent – will get the green light to start his spell in Scotland after being frustrated by a lack of game time in Belgium.
Despite this, Gershon is desperate to prove his fitness as he knows Efe Ambrose has been confirmed in Nigeria's final squad for the African Cup of Nations, which will see him miss at least three games.
Kelvin Wilson is suspended for the opening two, the SPL games against Hearts on January 19 and the re-arranged game against Dundee United three days later.
The latter was the league game postponed at the start of the season to allow Celtic to play Real Madrid.
It was originally rescheduled for December 15, but Celtic were told to play Arbroath.
A third date has now been agreed, and the bonus for Wilson is that he will be free for the Scottish Communities League Cup semi-final meeting with St Mirren.
Meanwhile, last 16 opponents Juventus last night defeated AC Milan 2-1 in the qurter-finals of the Italian Cup.
The visitors had taken the lead through Stephen El Shaarawy but Juve hit back through Sebastian Giovinco to take the tie into extra time, with Mirko Vucinic on target in the 95th minute.