Manchester United fought back from two down to beat Newcastle and avert a defeat that would have cranked up the pressure on manager Jose Mourinho.
The hosts conceded twice in a lacklustre first 10 minutes, with Kenedy and Yoshinori Muto breezing in to score.
United briefly roused themselves with Marcus Rashford heading wide from five yards, but also needed David de Gea’s excellence to deny Muto his second and a potentially decisive third for the Magpies.
The hosts departed at the break to jeers – some of which were aimed at the club’s owner and executives, rather than the manager.
But by the final whistle, it was the name of Mourinho that rang around Old Trafford.
All the reaction from Old Trafford
What else happened in the Premier League on Saturday?
The Portuguese, who brought Alexis Sanchez, Juan Mata and Marouane Fellaini off the bench in pursuit of victory, saw his side reenergised after the break and two of his three substitutes find the net.
As Newcastle dropped deeper, Mata swept home a free-kick with 20 minutes left to trigger an onslaught on the visiting goal.
Martial curled home six minutes later from Paul Pogba’s pass and, after goalkeeper Martin Dubravka pawed away Chris Smalling’s effort, Sanchez delivered the winner in the last minute of normal time, heading in Ashley Young’s cross.
Manchester United’s calamitous start
Yoshinori Muto marked his first Premier League start with a goal
According to one report on Saturday, the club hierarchy had decided before this game to get rid of Mourinho regardless of today result.
Their faith might have been tested by an astonishing opening.
As chief executive Ed Woodward watched on grim-faced in the stands, United’s defence crumbled, conceding twice in the initial 10 minutes of a Premier League game for the first time.
First, a lunging Nemanja Matic failed to intercept in midfield before Young tamely allowed Kenedy to turn onto his favoured left foot and fire in.
Three minutes later, the hosts were either too uncertain or unwilling to close down Jonjo Shelvey, allowing him to sweep into the heart of the box, where Muto easily turned Young and buried Newcastle’s second.
Mourinho, who had joked with former Chelsea charge Kenedy in the tunnel and playfully squirted a water bottle at a television camera before kick-off, appeared far less jovial by then.
As he gesticulated wildly on the sideline, his players looked at each other in apparent shock.