Aiden McGeady has to prove he's worth the fee, says Tommy Gemmell
• Aiden McGeady is believed to be in Germany to undertake a medical for Spartak Moscow Picture: SNS
However, the common belief is that McGeady, 24, would have preferred a move to the English Premier League and the Republic of Ireland player was linked with his former Parkhead boss Martin O'Neill before the manager suddenly quit Aston Villa on Monday.
But Gemmell, at Parkhead to publicise the club's free online video archive of Celtic action and history which is now available via their website, insists the Ireland internationalist has to show he can make the step up from Scottish football.
"Peter Lawwell (Celtic chief executive] has done a great job getting almost 10m from Spartak," Gemmell said.
"I get the impression Aiden was holding off to see if he could get a club in England.
"But with the size of the transfer fee, I don't think there would be a team in England who would be interested in paying that for Aiden McGeady.
"The way I look at it is he (O'Neill] wanted to sign Aiden McGeady and I don't think Villa wanted to go above the 5m limit.
"Aiden has got to go to Moscow and prove himself. If you don't do the business, there is nobody interested in you.
"He is still improving. He has a lot of things to prove to the football world and a lot of improvement to make in his own game. He has to gel with the players around him, which sometimes didn't happen at Celtic."
Gemmell, who played in two European Cup finals, including the Glasgow club's famous 1967 win, joked that the massive wages McGeady is set to enjoy - reportedly 40,000 per week - would help him overcome any difficulties he may face when it comes to adjusting to life in Moscow.
He said: "It's a tremendous deal for Aiden but it will be difficult for him to fit in to the Russian environment.
"But I'm quite sure with the small basic wage he'll be getting, he will manage it OK."
Meanwhile, Parkhead new boy Gary Hooper says he is looking forward to his first taste of Scottish opposition in a Celtic shirt when Neil Lennon's side travel to the Highlands on Saturday for their Clydesdale Bank Premier League opener against newly-promoted Inverness Caledonian Thistle.
The former Scunthorpe striker has already scored two goals for Neil Lennon's side - against Lyon in the Emirates Cup and Sporting Braga in the Champions League qualifier - but is now aiming to get his domestic tally up and running.
"I've not played against Scottish opposition yet so I still have to get used to the league and the players," he told Celtic's official website.
"But the matches against Lyon and Arsenal have prepared me well. It should be a good game and we're determined to win it.
"I don't know much about Caley Thistle, I haven't seen the stadium yet, but I will be ready to help win the three points if I get picked on Saturday," added the striker.