With potential replacements for his job reportedly being lined up in the wake of a disastrous midweek defeat in Como, Carrick made a big statement by dropping captain Bruno Fernandes to the bench for a potentially tenure-defining fixture.
Bournemouth, who thrashed seven-time European champions AC Milan on Thursday, were in no mood to follow the Old Trafford script, and they ought to have been ahead inside three minutes when Rayan headed wide of the far post.
Quality was in desperately short supply in an opening 30 minutes which failed to produce a shot on target at either end, but the Cherries’ control was eventually rewarded.
From a free-kick awarded for an Ayden Heaven lunge, Justin Kluivert’s delivery to the back post was met by an unmarked Rayan at the back post, where he applied a cushioned volley to break the deadlock.
An all-too familiar sinking feeling spread around the ground, and after Bryan Mbeumo was denied an equaliser by Djordje Petrovic, a slip from Leny Yoro gifted Bournemouth a second goal, with Adrien Truffer laying on for Marcus Tavernier to stroke into an empty net.
Vociferous boos greeted the half-time whistle, with Carrick surely left with just 45 minutes to save his United reign.
All eyes were on Fernandes ahead of the restart, but Carrick turned to Matheus Cunha instead and left his captain on the bench.
And within 30 seconds, Bournemouth had the ball in the net again through Evanilson, with Harry Maguire’s blushes only spared after a mistake by the offside flag.
Marco Rose’s men really should have been out of sight, but Rayan spurned a pair of glorious chances to add a third for the visitors when well placed.
There would be no reprieve for the hapless hosts, who were undone by a straight ball up the field by Lewis Cook, with both centre-backs leaving the ball for another and Senne Lammens not reaching the ball.
Evanilson rounded the Belgian, and from range at an acute angle, produced a miraculous finish to spark an Old Trafford exodus.
Bournemouth therefore scored at least three times for a fourth successive visit to United, and in the process secured their first set of four consecutive wins in all competitions since December 2023 - a streak that also included a 3-0 win on this ground.
United, who kept Fernandes on the bench, now look set to embark on another new era after seeing their winless run stretch to eight matches in all competitions.
Flashscore Man of the Match: James Hill (Bournemouth)
