Gary Megson fears Bolton run the risk of being dragged into another relegation dogfight if they fail to sign new players in the January transfer window.
The Trotters' Barclays Premier League status came under under severe threat last season before a late rally saw them scramble to safety.
The Trotters boss said: "We've got a really thin squad and that's something we've got to address in January because we won't get away with it again."
He added: "At the moment we are doing okay injury-wise because we've got an excellent medical team.
"They deserve a great deal of credit for helping us to work with a small squad. But we will be skating on the thinnest of thin ice if we try to get through the remainder of the season with the squad at its current size.
"Nicky Hunt is on loan at Birmingham and Heidar Helguson has gone to QPR, so that leaves us with just 16 outfield players.
"This is something that we had to sort out a year ago - the quality needed to come up but the quantity needed to come down. There has been a hatchet job done on the squad's size and now we've got to try and build it up again."
Megson admitted he also faces the threat of losing his best players.
Last season's leading scorer Nicolas Anelka was sold to Chelsea in the January transfer window - a huge gamble which almost backfired.
Megson added: "You never know what's going to happen if someone fancies one of your players and makes you an offer you can't refuse. That happened last year with Nicolas. Whether that will happen again I don't know."
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