Gary Caldwell says Rangers "over-celebrated" their win at Celtic Park and gave their rivals motivation to move clear at the top of the league.
Steven Gerrard's side won December's Old Firm game to move within two points of the Scottish Premiership leaders with a game in hand.
However, they have dropped eight points since while Celtic have won all of their games in 2020.
"I think it's fuelled the fire for Celtic," Caldwell said of his old club.
"They have come back after this break really determined, really driven and this is the time when momentum will play a big part.
"The game before the break that Rangers won was a big game. I felt like they kind of over-celebrated that game. There was too much emotion from Rangers when there was still a long, long way to go."
Caldwell won four trophies, including two league titles, at Celtic and was asked on BBC Radio Scotland's Sportsound if he saw any way back for Rangers in the race for the league, with Gerrard's men now 10 points behind, albeit still with a game in hand.
"I see Celtic winning it," Caldwell said.