Manchester United's capitulation at Stamford Bridge on Saturday was the clearest picture yet of a club eating itself from within.

A 2-0 defeat to Chelsea, sealed after Lisandro Martinez was sent off for a rash challenge on Wesley Fofana, leaves Michael Carrick's side 17th in the table and winless in nine matches across all competitions.

It also lands three weeks into a period in which two of United's senior players have publicly questioned the manager and the club's hierarchy from inside the dressing room.

The question now being asked around Old Trafford is not whether United have a results problem - that much is obvious - but whether the players themselves have become part of it.

Manchester United: A fortnight of dissent

The unrest did not begin at Stamford Bridge. It started on 13 October, when United lost 2-0 to Atletico Madrid in the Champions League and Martinez used his post-match interview to criticise the club's recruitment, singling out director of football Jason Wilcox and saying he expected more investment in the squad.

He stopped short of an apology at first, but after meeting Carrick and senior club officials two days later he apologised publicly; the club is understood to have fined him.

A week later, it was Bruno Fernandes' turn. After a chastening 4-1 Champions League defeat to Como on 21 October, the captain told TNT Sports that United had not pressed Como's defenders with enough intensity, adding that whether that amounted to criticism of Carrick's tactics was "on the manager and staff to see, not me."

Carrick responded by dropping Fernandes for the following Premier League match, a 3-0 home defeat to Bournemouth on 25 October that extended United's winless run to eight games and left them 16th in the table on seven points from eight games, one point above the relegation zone - their lowest points total at this stage of a season since 1986-87.

Manchester United: How Stamford Bridge unravelled

Carrick and Fernandes held direct talks before the Chelsea trip in an attempt to draw a line under the Como fallout, and the captain was restored to the starting lineup.

For an hour, the reconciliation looked to be working: United were the better side for long periods of the first half, with Fernandes, Amad and Matheus Cunha all missing presentable chances to take the lead.

The game turned early in the second half. Morgan Rogers split United's defence and lifted a finish over Senne Lammens to make it 1-0, and minutes later Martinez caught Fofana with his arm from a Chelsea corner, earning a straight red card and conceding a penalty that Cole Palmer converted.

Reduced to ten men, United's resistance collapsed, and Chelsea spent the rest of the match squandering chances to extend the lead further.

Manchester United: The case for sabotage

To United's critics, the word "sabotage" is not too strong.

Two senior players airing grievances about the manager and the hierarchy inside a three-week span, in a season already defined by results, is read by some as a dressing room no longer pulling in one direction.

Jamie Carragher said on CBS Sports that Martinez had been "bang out of order" for calling out the hierarchy, and took a similar view of Fernandes after Como.

Wayne Rooney went further, labelling the current squad "selfish" and accusing them of behaving like children rather than owning their performances.

Rooney, while defending Carrick personally, argued Fernandes' public criticism was a way of deflecting from his own drop in form this season, and said the pattern of players speaking out risked fracturing the dressing room at the worst possible moment.

On this reading, Martinez's red card - an undisciplined, arm-raised challenge with United already on top - fits a wider theme of senior players failing to show the control and restraint a manager under pressure needs from them.

Manchester United: The counter-case

There is a difference, though, between frustration and sabotage.

Martinez's grievance was about recruitment, not team selection: he wanted greater investment in a squad he felt had been left short, a view plenty of independent observers of United's thin depth would recognise, and he named no team-mate in making it.

Fernandes' critique of United's pressing against Como was echoed, not dismissed, by independent tactical analysis of the match, which found Fernandes himself was often the only United player applying sustained pressure on Como's defenders.

Neither player has questioned Carrick's suitability for the job directly, and both episodes were followed by conciliatory gestures rather than escalation: Martinez's apology and fine, Fernandes' private talks with Carrick and restoration to the starting eleven for Chelsea, and Carrick's own description of the decision to drop his captain as a football one rather than a disciplinary one.

The club's hierarchy reviewed Carrick's position after the Como and Bournemouth defeats and chose to back him rather than make a change - hardly the behaviour of a board being pushed toward the manager's exit by player unrest.

And for all the talk of a fractured dressing room, United were comfortably the better side for an hour at Stamford Bridge; what undid them in the end was a moment of individual indiscipline from Martinez, not a collective capitulation.

Manchester United: Where it leaves Carrick

What is harder to dispute is that United's results, not any single comment, are what is driving the crisis.

Nine games without a win, a defensive crisis compounded by suspensions and injuries, and now a 17th-place standing leave little room for Carrick regardless of how united his dressing room is.

Sabotage implies intent; what Stamford Bridge showed was closer to a team low on confidence, short on senior defensive options, and unable to see out a match it had controlled for an hour.

The more pressing question for United is whether public unrest and poor results start to reinforce each other - whether another bad week invites another outspoken interview, and another outspoken interview makes the next bad week more likely.

The hierarchy has given Carrick more time. His players, for now, say they support him too. Saturday suggested that support alone will not be enough to turn results around.