The champions moved four points clear of Rangers in the William Hill Premiership and eight above last year’s runners-up, who suffered more Celtic Park misery five months after losing their grasp on the title in the closing minutes of the season.

O’Neill’s side had lost four of their previous five matches and Hearts had arrived in Glasgow as the Premiership’s leading goalscorers.

But, despite the game being fairly even in terms of possession and shots at goal, Celtic were 5-1 up at the break.

Kieran Tierney and Benjamin Nygren netted from corners inside 10 minutes, Callum Osmand struck twice in two minutes and Jamie McCart scored an own goal after Mika Baur had waltzed through the Hearts defence.

Camilo Duran and Nygren completed the rout, with Laurent Mendy netting a consolation.

“It’s probably too early to worry about a message,” said O’Neill, who revealed Osmand had come off as a precaution because of a tight hamstring.

“But I thought we played really well.

“It’s very early. We were four points behind with about seven games to go last season, so it can be eroded very, very quickly.

“But it’s nice to win, and winning in the manner in which we did.

“From Hearts’ viewpoint, probably just a bad day at the office, but they’ll still be challengers, they’ve got some really decent players who can play a bit.

“If we lose on Thursday (against Celta Vigo), it’ll be crisis back again. I’ve been here before. You just have to try and win.”

Hearts head coach Wouter Vrancken admitted losing two early goals from corners had made life difficult.

“The mindset and confidence within the group changed, maybe, because what you saw afterwards was us trying to play football,” he said.

“Sometimes it worked, but when I look back at the goals, I think they all came from individual mistakes. We were losing the ball too easily.

“After the game, the most important thing for me is to get into their heads and make sure they don’t lose confidence in what they’re doing.

“I’d rather have players who are willing to take responsibility and make mistakes while still showing confidence, instead of hiding themselves because that doesn’t bring anything to the team.

“Of course, you want to minimise the mistakes, but when they happen, hopefully there are only one or two across the whole game.”

When asked if he would have made tactical amendments with hindsight, the Belgian said: “We have our style of play and the important thing with that style is maintaining the necessary aggression in those moments. We lacked that a little bit in the duels.

“When you’re not aggressive enough and you lose the ball or give it away too easily, it becomes difficult.”