Barton was told to train alone when he arrived at the Magpies' Darsley Park training complex yesterday morning, ending any hopes of a reconciliation between the 28-year-old and the club's rulers.
With his agent, Willie McKay, continuing to speak to a number of interested parties, Barton, who has been fined two weeks wages following Sunday's Twitter outburst, has been left in no doubt that if he opts to remain on Tyneside for the remaining ten months of his contract, he will effectively be in solitary confinement.
Newcastle officials are keen to see him leave as quickly as possible, in order to free up around £56,000-a-week in wages and thereby enable Alan Pardew to sign a replacement.
But while Barton is expected to have moved elsewhere by the time Newcastle kick off their Premier League campaign with a home game against Arsenal a week on Saturday, Enrique's departure from Tyneside could be rubber-stamped by the weekend.
Talks with Liverpool have advanced significantly in the two parties are now extremely close to agreeing an initial fee of around £6m, which could potentially rise if a number of conditions are met. The Anfield club will then discuss personal terms with Enrique's representatives.
Those talks could commence today, although they will not necessarily be simple as Reds boss Kenny Dalglish has recently spoken of a desire to trim his club's wage bill rather than increase it.
However, Liverpool's need for a new left-back is pressing, and sources close to the deal claim Enrique has expressed a desire to move to Merseyside.
Provided personal terms are agreed, the Spaniard will undergo a medical with Liverpool officials before becoming the second player to swap St James' for Anfield within the space of eight months.
With Andy Carroll having moved for £35m in January, Liverpool will have deposited £41m in Newcastle's accounts in less than a year.
What has happened to the bulk of it remains a moot point, although Pardew has cited signing on fees, agents' payments and an ongoing investment into infrastructural improvements at the club's training ground as a considerable drain on resources.
Whatever the merits of that argument, Enrique certainly appears to have played his final game for Newcastle, and his departure, while widely expected, will add to the growing mood of discontent among the club's supporters.
Enrique was one of Newcastle's most impressive performers last season, and his exit will leave Pardew with little more than a week to sign a new left-back ahead of the start of the new campaign.
The Magpies pulled out of a deal for Swansea's Neil Taylor when the Welsh club challenged the existence of a contractual clause enabling them to sign him for £1m, and while it is hoped Shane Ferguson will be fit to face Arsenal, youngster James Tavernier is currently the only left-footed full-back on the club's books.
Barton remains on those books for the moment, but yesterday's events underlined the extent to which his relationship with his employers is now irreparable.
As ever, the day could be tracked on Twitter, with the midfielder starting the morning by casting himself as the hero in an Orwellian battle for the truth.
Barton tweeted: "In times of universal deceit, telling the truth will be a revolutionary act. George Orwell"
Less than an hour later, he followed up with the message: "Made to train alone today, how predictable."
He is yet to hold formal talks with any of his suitors, although a number of top-flight and Championship clubs have approached McKay to signal their interest.
Aston Villa and Stoke are both understood to be keen to sign Barton, while former West Ham boss Sam Allardyce is hoping to reunite the one-time England international with his former team-mate, Kevin Nolan, at Upton Park.
McKay continues to talk of his client moving to a "Champions League" club, but despite previous links with both Manchester United and Arsenal, such a scenario appears unlikely.
Meanwhile, Wayne Routledge was at Swansea yesterday tying up the loose ends of his £2m move to the Liberty Stadium.
The winger is set to sign a three-year deal with the Swans, and could be involved in today's friendly with Celtic.