Celtic Thrashed Newcastle 4-0 when the Scottish champions celebrated the return of Kieran Tierney to the club -and alarm bells sounded for the Premier League side of Eddie Howe.
Alexander Isak and Joelinton belonged to a number of large absenters for the visitors, but a positive start was wasted when Joe Willock's mistake on Arne Engels the Belgian allowed the opener to score from the place before Nick Pope's Howler opened the door for Johnny Kenny to tap a second in a second.
Newcastle made nine changes during the break, including the introduction of new signing Anthony Elanga, but Celtic have capitalized on that shake-up, with Hyun-Jun Yang in a third after an impressive fast and slick counterattack.
The Celtic season starts two weeks ahead in Newcastle's and the progress of the Scottish side in their preparations was clearly visible. The home support enjoyed the performance and gave a huge welcome back to sign Kieran Tierney again, who came to Parkhead on Parkhead for the first time in six years, after his enchantment with Arsenal.
There was an even bigger roar when he crossed for another submarine, Liam Scales, to go into goal number four.
The hoops are bouncing on Thursday in their last pre -season match against Ajax, while Newcastle is now going to Singapore for a collision with Arsenal.
About 10,000 fans of Newcastle made the trip to Glasgow for the first pre-season game in public. They will hope for considerable progress on the field and on the transfer market before their campaign starts next month.
Analysis: Loss of Newcastle shows the need for signing sessions
Sky Sports News' Keith Downie in Parkhead:
“Newcastle was taught a little lesson today. I know that Celtic is in terms of terms of preparation for the season – they have been a few weeks ago – but there has been a gap between the teams.
“Yes, Newcastle miss the will of Isak, Joelinton, Tino Livramento and Lewis Hall, but Celtic has been ahead of his streets.
“Newcastle fans will think they should add more signing sessions – they have only added Elanga this summer so far, but with this show they need a few more.”
Sky Sports to show 215 Live Premier League matches from next season
From next season, the Premier League coverage of Sky Sports will increase from 128 games to at least 215 games that are exclusively live.
And 80 percent of all Premier League matches broadcast on television will be on Sky Sports next season.