JOE HART insists it was no surprise to the Celtic squad to hear Ange Postecoglou was disappointed despite victory over Livingston.

The Celtic boss was disappointed with performance levels in the 2-1 triumph at Parkhead as he cited his “principles of play” which were somewhat lost in the league win.

Postecoglou was happy with the three points to keep Celtic boasting a nine-point lead over Rangers, but he wasn’t shy in telling his players and the press that the performance wasn’t up to his sky-high standards.

Hart could already tell he and his team-mates were set for an honest conversation with the manager after the final whistle even before he took a seat in the dressing room. But the keeper wasn’t at all surprised as he saluted the actions of “honest” Postecoglou.

“It’s not a side that we don’t see,” said Hart when discussing the disappointment voiced by the Celtic manager. “That’s what we see from him. He expects a lot from him and we expect a lot from ourselves. 

READ MORE: Ange Postecoglou refuses to wade into Celtic VAR debate

“He’s certainly not going to walk in - after a game when we’ve maybe not taken the chances to put the game out of sight and it’s turned into a difficult second-half - and not say that.

“I think you guys in the media appreciate that and we do too. He’s pretty clear with us and honest with his feelings. He lets us know.

“But it’s not a shock, it’s not a bolt. We know it’s coming. We know when we are playing well and when our flow is good.

“But he regularly points out to us that it’s all very well and good to get to a certain height. But the higher you get the harder it is to stay at that level.

“He wants the best for us. But there are different ways of getting that out of us and he can’t be nice all the time.”

While Hart and Postecoglou have both admitted performance levels against Livingston were perhaps a little below the Celtic standard in recent months, it’s not lost on the keeper how important the victory remains in the league title race.

And crucially, Hart is adamant Celtic will return to their best against St Johnstone – even if they weren’t “bad” against Livi.

“Obviously it was an important win in the context of the league,” said Hart reflecting on the match.

“We would have loved to have played a lot better and scored more goals but we got it done.

“We played well last Saturday at Aberdeen and were comfortable in that perforce and got a well earned win.

READ MORE: Postecoglou in 'not how it works' reply to Abada Celtic hypothetical

“Against Livingston I felt we were really good - until they scored.

“In the second half we weren’t as good as we like to be. But it was one of those, we weren’t particularly good but we definitely weren’t bad.

“We would have liked to have scored a few more. But football is not set up for us just to smash people all the time. We have to earn it and we have to put the ball in the net.

“We have high standards here, though, and we want to keep playing to those standards. We now have another opportunity against St Johnstone on Saturday.”

An own goal and a Kyogo Furuhashi strike was enough for Celtic to take their tenth successive victory even if Nicky Devlin’s finish on the stroke of half time ruined Hart’s hopes of a clean sheet at home.

Celtic still boast the best defensive record in the Scottish Premiership table with 14 goals conceded after 17 matches. They’re also far and away the top goalscorers having netted 53 times already this term.

For Hart, it all comes down to the monumental team effort and group work ethic from the “exceptional” forward players back to the goalkeeping “unit” both playing and on the sidelines.

“I think they’re exceptional players,” Hart said when discussing his attacking team-mates.

“We have some real young talent who have a great understanding of how we play.

“Their football intelligence is right up there.

“But do you know what I love about them most? It’s that they buy into the team ethic.

“I’ve played with many strikers and forward players who you kind of let them do their thing and they score goals and have their moments.

“But we’re a unit and right from myself, Benj and Bainy to Kyogo and Giako. We are all one and all want to move forward together.

“I can’t see that changing, if I’m honest. Because none if us will let that happen. 

“The only way we’re going to be successful is if we’re together and pulling in the same direction.

“With the football we play, we have to play as a unit and a group. Because if we don’t then it breaks down.”