Celtic manager Brendan Rodgers stressed that hard work and mentality would be crucial during a busy December for players who are in and out of his side.

Rodgers claimed he was the angriest he has ever been as a manager at half-time at McDiarmid Park on Sunday with Celtic trailing 1-0.

His players reacted to his accusations they had been “soft” in the first half and went on to beat St Johnstone 3-1.

“For me, it’s very, very straightforward, football,” Rodgers said. “What you gain through experience, and when you take away the technical jargon, the difference in the game is about working hard.

“And when you are a top team, it’s about working very hard. We failed to do that in the first half and if you don’t do that, you can get punished, with any team.

“So you always have to guard against that. No matter how good a team you are, the start point for any team is your work. And once you put your work in and play to the intensity and speed of which you are asked to play, you see the difference it makes.

“There was nothing tactical about Sunday, it was about mentality and physicality and once you bring that to the game you get your rewards.”

Rodgers has spoken of the need to strengthen his squad in recent weeks despite admitting he has too many players.

Such comments might not give much encouragement to those who are unable to break into his team, including summer signings Maik Nawrocki and Gustaf Lagerbielke, who are being kept out of central defence by Cameron Carter-Vickers and Liam Scales. But Rodgers has told his squad players to keep believing.

“I am out there every day watching training,” he said. “And when I see players training and working with that personality then they will always edge their way closer to my thinking.

“I have said before it is clear our squad is quite big. Unfortunately for the likes of Maik and Gustaf, Scalesy came into the team and really took his opportunity. Nat Phillips has been brilliant since he has been here, he has been a real positive influence, and it’s the one area of the team you don’t want to change too much when both players are fit.

“So for any player it’s all about what they do in training and that is all they can do. You can’t get too disappointed. If you are working hard, then hopefully those opportunities come for you.

“All the guys who came into the game (on Sunday) affected it. The modern game is not now just about the 11 players who start. Guys like Mikey (Johnston) coming into the game was outstanding, very direct, fast and was creative, and worked hard. Jamesy (Forrest) gets his goal, Tommo (Tomoki Iwata) comes in and creates the third goal.

“That’s testament to how they train, the intensity of our training every day allows them to be at a good level so when they come into the game they make an impact.”

Rodgers will have Luis Palma available for Wednesday’s cinch Premiership encounter with Hibernian after the winger went off with cramp in Perth.

Injured trio Daizen Maeda, Liel Abada and Reo Hatate are still to return to full training.

“Liel and Daizen are both on the pitch now which is great news,” Rodgers said. “Daizen is probably a little bit ahead of Liel, but I am expecting at some point this month they will be available.

“They are back out on the field with the medical team and the rehabilitation team, and hopefully it won’t be too long before they will be back in with the squad again.

“We allowed Reo to go back to Japan and he has worked very hard there. He returns later in the week and we will assess him when he comes back.”