Liverpool fans picked up on a cheeky detail as the club shared a video of Virgil van Dijk and Alexander Isak greeting each other at the training ground on Friday morning.
Isak reported back from international duty earlier than Van Dijk, with the Swede taking part in his first Liverpool training session on Wednesday, but the skipper was back on site at the AXA Training Center on Friday ahead of Sunday's trip to Burnley.
Van Dijk walked into the building and shook hands with Isak before hugging his new teammate, and in the background, 'Rein Me In' — a song by Sam Fender, one of Newcastle's most famous fans — was playing.
It didn't go unnoticed by Liverpool fans on social media, with some clearly of the opinion that the Reds had intentionally played that song to goad Newcastle supporters over the striker's deadline day move to Liverpool.
"Sam Fender playing in the background is a great bit," one Liverpool fan wrote, while another said: "Sam Fender playing in the background is a lovely bit of s--- housery."
Isak could make his debut for Liverpool at Turf Moor this weekend, but he is unlikely to start the game having only played around 20 minutes of competitive soccer since May.
Isak effectively went on strike at Newcastle in a bid to force through a move to Anfield: he missed the Magpies' preseason opener against Celtic, and refused to travel on the club's tour of China.
Isak did not figure in any of Newcastle's opening three Premier League games of the season, either, before his determination to join Liverpool paid off on deadline day as he secured a move to Merseyside. After signing for Liverpool, Isak quickly jetted off on international duty as Sweden faced Slovenia and Kosovo in World Cup qualifiers.
Isak, though, did not play in the 2-2 draw with Slovenia and only featured as a substitute for around 20 minutes in the 2-0 defeat by Kosovo.
Addressing Isak's readiness to play for his new club during a press conference on Friday, Liverpool head coach Slot said: "First of all I think the Swedish manager, Jon Dahl Tomasson, deserves a big, big, big compliment because he gets one of the best, maybe the best striker in the world in and needs to play two very important games for his country, but understands if he would play him twice for 90 minutes the player would have probably been injured for multiple weeks.
"That is not always easy for a manager, that he takes care of the interest of the player, so he deserves a big compliment for that and we will treat Alex the same as they did.
"So, don’t expect him every single game 90 minutes on the pitch – that’s definitely not going to happen in the upcoming weeks.
"He missed a proper pre-season, I think he missed three or four months of team sessions, so now we have to build him up gradually with us playing so many games and [having] very little training time.
"So, that’s going to be a challenge but we’ve signed him not only for the upcoming two weeks, we’ve signed him, I think, for six years so this is what we have to keep in mind and what the fans have to keep in mind if they see that I take him off at a certain moment or I only bring him in for a small amount of minutes. That’s all for the long-term fitness of the player."