Raheem Sterling’s confrontation with Joe Gomez lasted only 10 to 15 seconds according to those present, yet the fallout from it will run significantly longer for England, Gareth Southgate and the FA.

The incident, which led to Sterling being dropped for the game against Montenegro on Thursday evening, took place at about 12.30pm on Monday at St George’s Park.

Gomez was in the canteen shaking everyone’s hand and then reached Sterling, who was sitting down. Sterling snapped and responded, “So you think you’re the big man?”, stood up and tried to get Gomez in a headlock, knocking food over from the table. “It was a pretty full-on thing and food went everywhere,” said one source. “Sterling behaved like a bit of a child.”

Another source said: “It was all out of the blue, ‘Woah, what the hell has happened here?’. Everyone was just a bit shocked.”

The roots of Monday’s incident lie in Sunday’s Premier League game between Manchester City and Liverpool. Sterling was goaded by the Anfield crowd and subjected to chants of “one greedy bastard” about his 2015 transfer from Liverpool to City.

Traditionally, Sterling has under-performed in that fixture and has been substituted early three out of four times before Sunday. But this time, Sterling was City’s best player in the 3-1 defeat, and was thought to have been devastated by the outcome. Sterling tussled with Gomez late on during the game and appeared to tread on Virgil van Dijk towards the end.

Although Sterling and Gomez made up after the final whistle on Sunday, images of Gomez pushing Sterling widely circulated online on Sunday evening, giving rise to a feeling that Gomez had “embarrassed” Sterling. So it was an emotional Sterling who arrived at St George’s Park on Monday morning. Gomez was the first of the Liverpool players to arrive, before Trent Alexander-Arnold or Jordan Henderson.

Gomez had initially thought Sterling was joking, and a handful of team-mates laughed at the City player’s initial comment. But when it became clear that Sterling was serious, Gomez moved backwards and the pair had to be separated by concerned team-mates.

Gomez is thought to have been very upset by the incident. The softly-spoken defender does not like confrontation and did not think there would be any issue with Sterling following their embrace after Sunday’s match. But he decided, in the words of one source, to “take the moral high ground” in the interests of “what is best for the team”.

Liverpool are also thought to be angry that Gomez has been put in this situation through no fault of his own. The 22-year-old was seen to have a scratch under his right eye when pictured at training on Tuesday morning.

While Sterling’s behaviour has surprised some sources, there is also a view from those who know him well that he is more competitive and driven than many realise. And that defeats as important as Sunday night matter more to him than they might do to other players.

It is also not the first time Sterling and Gomez have clashed on England duty. This is a story Southgate told after England played Kosovo in Southampton in September.

“Raheem will give himself every chance, because he’s got the drive, he’s got the professionalism, he’s got the ability, he’s strong, he’s physically and mentally strong for such a small-statured lad,” Southgate said. “It was hysterical the other day, he and [Joe] Gomez had a shoulder-to-shoulder moment. And of course, they were bantering about it for the rest of the week.”

Southgate was not amused by their latest confrontation and there is also frustration and disappointment among FA officials that the incident has overshadowed an incredible amount of hard work and planning that has gone into preparing for the celebrations of England’s 1,000th game.

Sterling was initially sent home by Southgate on Monday night and it took an intervention from England’s senior players to change the manager’s mind, with him allowing Sterling back into the squad as long as he apologised to Gomez.

Sterling was on the way out of St George’s Park when his car turned around and he went back, waiting for Southgate and the senior players to decide his fate. Sterling apologised to Gomez and Southgate convened an emergency team meeting at 9pm, when the manager confirmed Sterling’s suspension for Thursday night’s game with Montenegro.

That decision, along with the public announcement at 11pm confirming Sterling’s dropping from the Montenegro game, has sparked anger from those who work closely with the player. There is a sense from one source who knows Sterling well that the FA has overreacted to the incident, and that rather than doing the right thing, it has prioritised being seen to do the right thing.

“Back in the day, you were always having training ground bust-ups,” said one source close to the squad.

“That was part and parcel of the culture. Some managers would step in, some managers would let it go. I’ve never known something happen for 10 to 15 seconds and one lad gets kicked out. It makes me think this is all about the PR for Southgate.”

The former England defender Rio Ferdinand also said that the incident could have been “handled better” and that confrontations on international duty are more common than might be expected. Although one source pointed out that the Manchester United and Chelsea players managed to play for England days after the 2008 Champions League final without club rivalries spilling over into confrontation.

After Southgate decided to send Sterling home, it took lobbying from the team’s leadership group, including Henderson, to change the manager’s mind, and decide that an apology accepted by Gomez would be enough for Sterling to rejoin the squad.

“Raheem had to go calm down, then he realised what he had done was wrong, and he apologised profusely,” said one source. “Not straightway but pretty quickly. He grovelled all day. It’s done, finished. A line was drawn through it, to focus on the game on Thursday.”

There was no immediate statement from the FA, not until 11pm on Monday night. But they knew how serious an issue it would be. The FA technical director Les Reed was with associates at Twickenham for the Leaders Sport Business Summit but he had to withdraw from a planned dinner, saying that his phone would be ringing the whole evening, so he should not come to the meal.

But there is still a view that the FA’s suspension of Sterling, and the public announcement of it, has made this a bigger issue than it otherwise would have been. “It all seems overblown,” one Premier League sporting director told The Athletic.

“I would expect my manager to sit them down, keep it in-house. Instead, Southgate has given a lot of oxygen to what sounds like a 10-second event.”