CELTIC manager Ange Postecoglou called for fans to "protect the sanctity" of the 90 minutes after the start of his side's 4-2 victory over Dundee was disrupted.
Dozens of tennis balls were thrown on from the away fans at Dens Park straight after kick-off in a protest at claims that Celtic are set to appoint Police Scotland assistant chief constable Bernard Higgins in a senior security role.
A banner addressed to acting chief executive Michael Nicholson stated: "Fans or Higgins? Ball's in your court."
The protest was a change of tactic from the previous Saturday, when Celtic fans sang no songs at all during the first half hour of a flat goalless draw with Livingston at Parkhead.
Several of Postecoglou's players helped clear the balls off the pitch and the delay did them little harm with the visitors going two ahead inside 20 minutes.
When asked about the tennis ball protest, Postecoglou said: "My view on all those kind of things is that we live in a society where people are allowed to express themselves.
"It's not necessarily a bad thing but I'd rather protect the sanctity of that 90 minutes because I know how precious it is and if we want to be a successful team we need everyone united for that."
The protest followed a disrupted Remembrance Day's silence which was cut short after some Celtic fans started singing a song about Aidan McAnespie, who was shot dead at a British Army checkpoint in Co Tyrone in 1988.
When asked about that incident, Postecoglou said: "Again, you would have to ask the individuals why they felt the need to do that.
"My view again is pretty simple, that we treat these things with respect and dignity and that's what we try to do.
"We certainly did and I think the majority of the fans did because that's the kind of football club we are."
Celtic ultimately triumphed thanks to doubles from Kyogo Furuhashi and Jota but the scoreline did not quite reflect how dominant Postecoglou's team were.
Dundee twice responded after a brace of early goals in each half, when both Danny Mullen and Lee Ashcroft headed in crosses from Paul McMullan.
Postecoglou said: "We played some excellent football at times and controlled the game and played it on our terms. We scored four great goals and we could have been a little bit more ruthless in front of goal.
"We were disappointed to concede two goals. We just got a bit sloppy for both goals and part of our progress is to understand that we can't lose focus or take liberties with our game."
Dundee boss James McPake took encouragement from the fact his side did not wilt given they had lost 6-0 at Celtic Park in August, and 5-0 against Ross County in their previous home match.
"Ultimately, the third goal kills the contest to a degree and it's a poor goal by our standards," McPake said. "The players are annoyed at that.
"But they kept the character, they kept fighting.
"There have been games this season, you think back to the Ross County one, when that was not there.
"If we'd have kept it tight for the first 10 minutes of the second half, we could have gone and had a go and tried to get ourselves really back into the game.
"But Celtic are very hard to deal with and that was shown."
