Marcus Rashford went close within the opening stages but his effort was well saved by Oblak. Then Anthony Martial then should have made it four goals in pre-season after blazing over in the first half.
Atletico’s best chance of the first half arrived when Angel Correa broke through but the Argentine failed to find the target. But after the interval, Diego Simeone’s side looked more attacking as they went for the win.
Saul, who returned to Atletico from a disappointing loan spell at Chelsea, almost gave Atletico the lead in the 70th minute but he fired wide, before Felix opened the scoring.
The Portuguese star — who has been linked with United this summer — took his time before finding the back of the net from 20 yards out to hand the Spanish side the lead.
And United’s pre-season schedule ended on a sour note as Fred, who had impressed in the centre of midfield, was shown a red card in stoppage time to hand Ten Hag his first defeat as Red Devils boss.