KRIS COMMONS sat in the small, antiquated away dressing room deep in the bowels of Tynecastle and felt the darkness descend.
It had replaced the bright red he had been shown by the referee just minutes earlier after an un-Commons-type foul on Adrian Mrowiec had led to his dismissal.
Now, though just yards from the vociferous crowd on the other side of the wall, he felt alone.
Alone with only his thoughts for company. And he didn't like what they were saying about him.
"I'd been injured or had not played for a little while, just getting a bit part as a sub here and there," he recalled of what he admits was the lowest point in his very-troubled second season at Celtic in October 2011.
"Then I got the nod to play against Hearts - and I got a straight red.
"I just went back into the dressing room and said, 'What's happened here? I have not scored a goal, I am not playing, getting red cards for reckless challenges. That's not me. I don't do that.'
"That was a bit of a dark time."
Fortunately, with the support of manager Neil Lennon, his team-mates and his wife, Lisa, Commons dragged himself up from the floor and eventually rediscovered the form which had made him an instant success when he had joined the club from Derby just 10 months earlier.
Since then, Commons has never looked back, the trajectory of his career in Hoops lifting him to the status of one of Lennon's most trusted players, a first pick, and, this season, his leading goalscorer.
However, the intelligent 30- year-old refuses to forget just how bad his second season-itis was.
Even as he holds aloft his first SPFL Player of the Month award, he insists on using his unhappier memories as the yardstick by which he measures his subsequent success.
Commons explained: "You have to take football as a package. The bad times make the good times even better.
"Footballers don't just have illustrious careers and great highs all the time.
"You have to have those lows to make the highs as good as they are.
"I'm probably grateful that, these times when I am enjoying it, picking up awards and scoring goals, I can keep my feet on the ground because I know how bad it can be."
Season 2011-12 remains raw for him, and he still does not know why it happened.
Having hit the net 15 times in the four moths after he moved to Parkhead in January, the slump in form hit him like a sledgehammer, cracking his confidence and leaving him numb.
"It was one of those seasons which had never happened in my career before," he reflected. "I'd gone from coming in, scoring goals, and doing really well to picking up injuries and not playing well.
"My form was terrible, so I couldn't argue about not playing. But two months earlier I had been playing really well, and I just didn't have the answers.
"When you are playing badly, and you're injured all of the time, you tend to try even harder and end up making yourself worse. It was a bit of a learning curve for me."
Despite his problems, and ill-informed reports of a bust up with Lennon, running back to England was never an option for the man from Mansfield.
Asked if he would have taken a way out of Parkhead, had it been offered, he replied instantly: "No, never. This is the best club I've ever played for."
Arguably, it is also the best he has ever played, which, at 30, is testament to his determination and drive. The fact he is the top scorer at the club this season, with 17, is a bonus.
But he almost baulks at the suggestion he is aiming to be at the top of the scoring charts when the campaign ends.
"I train every day as well as I can to stay in the starting XI," he said.
Scoring goals is merely another vehicle to take him where he wants to be - in the starting XI.
"I know the gaffer can change the team whenever he wants," he continued. "We've a lot of players always itching to start games.
"So I have tried to keep my feet on the ground, always aware he could drop me.
"I have to keep performing week in, week out, so I'm one of the first on the team sheet.
"And, when chances come my way, I do my best to put the ball in the net."
Again, the lessons of that second season are at the heart of his work philosophy.
"I suppose I probably took it for granted, you expected to be playing week in, week out," he recalled.
"When you are playing at such a calibre of club as Celtic, it's brilliant to be playing in front of the fans, brilliant winning trophies, and superb playing in the best competition in the world.
"But, when you're not involved, it's one of the worst places because you know you are missing out."
Not that Commons is missing out on much these days, except perhaps the Champions League, following Celtic's early exit this time around.
But that has been balanced by the remarkable form they are showing in the league, the correlation between the two readily acknowledged by Commons.
Already, eyes are drifting towards next season's qualifiers. And, Commons hopes, many more campaigns in the Hoops after that.
He has a year of his contract to run, with the club holding a further 12-month option.
Lennon has already spoken publicly about taking up that option, but Commons laughed: "I saw that on the back of the papers, but I've not heard anything about it yet.
"I'm still looking for this three-year deal (another report). Is that floating around anywhere?
"I'd like to stay here, so it's important for me to keep playing, keep scoring, stay in the manager's eye and see where it take us."
There has also been mention from Lennon he would like to eventually co-opt Commons onto his coaching staff.
But, again, the player is cautious. He said: "When I'm bit older, it may interest me.
"But I'd like to think there is something other than football that I could venture into.
"It's another thing I'm going to think about seven or eight years down the line. I don't know what, but, when you have done just one thing all your life, you think there's got to be something else.
"My missus is big into charity and tries to help as many people as possible. There may be an avenue there, I don't know."