Crewe used their senior players to great effect in Monday's U21s fixture at Bramall Lane.
Nathan Ellington, Max Clayton and Byron Moore, who between them have racked up more than 750 senior appearances, were the difference and scored all the goals against a Blades team whose only recognised first team regular was Marcus Williams.
The Blades created the first chance but Eyre's shot was saved by Garratt, but from then on it was downhill for the hosts. ELLINGTON, who had already gone close, opened the scoring on 12 minutes when he got between United's central defenders to head home Clayton's cross.
The lively ELLINGTON also added the second. With 26 minutes gone, his free-kick beat the wall and wrong-footed goalkeeper Willis.
The Blades had a chance to get back in the game soon after when Bunn's shot was saved by Garratt and the loanee was fouled as he looked to pounce on the rebound but no penalty was awarded.
At the other end, though, the referee did point to the spot on 32 minutes when Willis brought down Moore after a mistake in midfield. CLAYTON stepped up and although the Blades goalkeeper did dive the right way, he was beaten by power.
Three became five with further goals on 44 and 45 minutes. Firstly Clayton caused problems on the left and MOORE did well to turn the ball home beyond the far post. Just before the half-time whistle CLAYTON added his second with a neat curler after a pass from Ellington.
Playing for pride in the second half the young Blades continued to battle but Crewe were the stronger offensive force. Willis saved from Turton, Ellington fired wide and Clayton was denied a hat-trick by a linesman's flag.
For United, Dimaio shot wide and Banton's near post header was saved by Garratt. There were further Crewe chances later on - including Ellington shooting against a post - but the Blades held on to keep the second half score level.
It was the first defeat of the season for United's U21s after a victory over Sheffield Wednesday and draws with Birmingham City and Nottingham Forest.
Blades: Willis, Hodder, Williams, Dimaio, Evans, Banton, Bunn (Cockerline 72), Whiteman (Scarisbrick 64), Smith, Eyre, Johns (Kedman 82).
Unused: Owen, Coustrain.