Celtic's players are not giving 100% under manager Ronny Deila, according to the club's former winger Joe Miller.
Deila and his players are having a clear-the-air meeting after Aberdeen narrowed the gap at the top of the Scottish top-flight to four points.
"Those talks usually come about when a team's struggling." Miller told BBC Radio Scotland's Sportsound.
"He [Deila] picks a team and they should be going out there giving 100%. I don't think they are."
Deila said he understood why he and his players were booed off the field by Celtic supporters after the goalless draw at home to Dundee.
"We need to clean the air and be agreeing with how we go forward," the Celtic manager added.
"That's my job to do. That's what I'm going to do.
"The players give 100%, but I don't get 100% out of them," he said. "They can play better than they did last night.
"It's about confidence. We haven't performed in some games and we need to turn that around."
Aberdeen's 1-0 win away to Dundee United drew the second-placed side to within four points of the reigning champions.
However, Deila believes that the fans will still back him and the players despite their frustration.
"We need to get back together," added the Norwegian. "The fans will stand behind us because they're Celtic fans.
"We have to show we want to fight for it. A wrong pass can happen, but we need to see desire on the pitch.
"I understand the reaction to last night. We didn't create anything.
"We looked tired. We need to turn it around."
Miller, who played for Celtic from 1987 to 1993, added: "It happened to me at Aberdeen when Willie Miller was the manager and it's the sign of pressure on the manager, the staff and the players.
"It surrounds them every day in training and then when the go out on a Saturday the confidence isn't there and they don't get results.
"So, when they're having sit-down talks it's worrying.
"They're trying to do something about it and be pro-active. Sometimes you can air that and get everything off your chest.
"But the bottom line is that players have got to produce the goods. Ronny Deila's not the man who's kicking the ball, it's the players."
A managerial change may help to galvanise Celtic's title challenge, Miller added.