Schwarzer emulated those heroics by flicking over Rafael's fizzing 20-yard effort as the Reds sought to safeguard victory. Sir Alex freshened up his central midfield with the introduction of Ryan Giggs for the final ten minutes, with Anderson making way. Another substitute, Hugo Rodallega, then forced a fine sliding block from Carrick after a neat through-ball from Ruiz.
Rooney fired narrowly past the top corner after latching onto Cleverley's intelligent through-ball, but the afternoon ended on a sour note for Rooney when Rodallega accidentally raked his studs down the England striker's inner thigh, leading to a lengthy stoppage with the game already in injury-time.
A dismaying end to the game might have plunged even further for United, who required another De Gea save - this time to fend away Ruiz's header - to preserve a hard-fought, bewildering win. Nevertheless, the Reds are off and running for the new season.