Shaun Miller hit a first-half brace as Crewe grabbed their first home win of the season with a 3-1 triumph over Oxford.
Ajay Leitch-Smith netted a third before Liam Davis scored a consolation for the unlucky U's, whose four-game unbeaten run came to an end.
Miller was denied an opener by United goalkeeper Ryan Clarke before Alex defender Dave Artell wasted a great headed chance from five yards.
But Miller made no mistake on the half-hour mark when Danny Shelley teed him up to lift the ball into the roof of the net.
Seven minutes later and Miller grabbed his second of the afternoon, side-footing home Leitch-Smith's perfect centre after Shelley's clever back heel kickstarted the move.
United deserved more from the game, though. Crewe keeper Steve Phillips had to keep out a stinging effort from Alfie Potter and a last-ditch block from Adam Dugdale denied Dean Smalley after the striker had pounced when Phillips could only parry Asa Hall's fierce 25-yard rocket.
Phillips then produced a stunning one-handed save to keep out Smalley's powerful header before Potter fired over and saw another shot saved by the keeper.
But the Alex hit the visitors on the break, Luke Murphy lifting the ball over United's back four for Leitch-Smith to bring down and drill home with 66 minutes gone.
Davis headed in Josh Payne's cross at the far post in the 77th minute and then rattled the base of a post with a stunning 30-yard strike, but it was Crewe who walked away with all three points.
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