Agathe was a part of the Bhoys side that went 77 games unbeaten at Celtic Park between 2001 and 2004.
Former Celtic wing-back Didier Agathe believes that teams are no longer afraid of coming to Parkhead, and hints that the Bhoys' struggles in front of their own fans may prove costly come the end of the season, The Scottish Sun reports.
Ronny Deila's side's last three defeats in all competitions have come at Celtic Park - including last weekend's surprise loss to struggling Motherwell - and Agathe suggested to The Scottish Sun that recent results have shown that opponents now come to Parkhead believing that they can come away with a win.
"It surprises me that Celtic Park has lost its fear factor. It has always been something that the club is known for," he said.
"I don't know what Celtic can do to get the fear back and make the stadium an intimidating place again.
"But it's clear that teams are now coming to Celtic Park believing they can get a win.
The other two defeats in front of their own crowd came during Celtic's disappointing Europa League campaign. Agathe - who was part of the side that went 77 home games unbeaten between 2001 and 2004 - suggested that for a team to be successful, they must be ruthless at home, perhaps suggesting that a continuation of recent results may see the Scottish Premiership title slip from their grasp.
"That is a problem that the manager and his players will have to solve as your home form must be strong," he added.
"That's what helped us have so much success in Scotland and in Europe."
While the side's home form is not as dominant as Agathe would like, Celtic remain in a commanding position in the league. They are one point clear of Aberdeen at the top of the table, and have a game in hand to potentially extend that lead.
And with their European campaign already over, Deila's men have the chance to concentrate on the league - as well as the domestic cup competitions - and prove to their top flight rivals that Parkhead is still a fortress.