January signing Austin rose unmarked to power in James Ward-Prowse's free kick in the 87th minute as United lost its first match in five league games.United supporters again vented their anger toward Van Gaal after watching another dull performance at Old Trafford. Boos rang out around the ground at halftime and following the final whistle as Saints recorded only their second win at United's home since 1988, but also their second in 13 months.
United fell back in its chase for a Champions League spot. It provisionally remains fifth, three points above Liverpool.
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