Day played 39 times for Rushden and Diamonds before his summer move
Aldershot have signed Crawley Town defender-midfielder Jamie Day on loan until 7 January.
Under the terms of the deal the left-sided 25-year-old will not be able to play in FA Cup games but goes into the squad to face Gillingham on Saturday.
Day joined Crawley from Rushden & Diamonds in the summer but underwent back surgery soon after.
The England C international made 112 appearances for Peterborough United with whom he won two promotions.
Shots boss Dean Holdsworth told the club website: "I have watched Jamie for a number of years.
"He brings excellent defensive qualities and is a strong acquisition to the squad and will provide healthy competition for places."