Portsmouth have signed keeper Mikkel Andersen, midfielder Conor Clifford and defenders Paul Connolly and Kevin Long on one-month loan deals from Reading, Chelsea, Leeds and Burnley.
All four are eligible to play in Saturday's League One opener against Bournemouth at Fratton Park.
They take the number of new faces to 14 after 10 players signed on Thursday.
Pompey are in administration and saw all their senior players leave this summer in a bid to avoid liquidation.
Danish goalkeeper Andersen, 23, has been at the Madejski Stadium since signing from AB in 2007.
"We're delighted to get Mikkel," said Pompey boss Michael Appleton.
"There was a fear we couldn't do it, but [Reading boss] Brian McDermott has been a different class."
Andersen has yet to play for the Royals, but has enjoyed loan spells at Torquay, Rushden & Diamonds, Brentford and Brighton.
He also spent 16 months on loan at Bristol Rovers, making 61 appearances.
Republic of Ireland Under-21 international Clifford, 20, arrived at Stamford Bridge from Crumlin United as a schoolboy and in the last two seasons has enjoyed fruitful loan spells at Plymouth, Notts County and Port Vale.
Clifford, who appeared in Pompey's final two pre-season friendlies against Bolton and AFC Wimbledon, has already been a member of Ireland's senior squad.
Defender Connolly - who began his career at Plymouth - has made 68 appearances during his time at Elland Road.
The 28-year-old joined Leeds from Derby in the summer of 2010 after playing 72 times for the Rams.
Irish defender Long, 22, has yet to make a senior appearance for the Clarets.
He arrived at Turf Moor from Cork City in January 2010 and has spent much of the time since on loan at Accrington Stanley and Rochdale.
Pompey have received Football Association and Football League clearance for the 10 players signed on Thursday.
However, international clearance has not arrived in time for midfielder Liam Walker to take part against Bournemouth.