Southend have extended the loan of Swindon defender Sean Morrison until January 9.
The 18-year-old want sent off on his Shrimpers debut but has impressed in his four subsequent appearances.
He will now remain with the Roots Hall club until their League One tie with Walsall.
Meanwhile, United's clash with Millwall that was initially scheduled for January 3 will now be played on January 26.
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