League Two Portsmouth have signed Nyron Nosworthy from Blackpool and Queens Park Rangers' Cole Kpekawa on loan until the end of the season.
The defenders have been brought in after Pompey manager Andy Awford confirmed defender Jack Whatmough would likely miss the season through injury.
Former Watford centre-back Nosworthy, 34, has played five games for the Championship's bottom club this season.
Kpekawa, 18, has spent much of the campaign on loan at Colchester.