NEIL Harris has warned that Millwall's squad may not be finalised until the last day of the January transfer window.
Lions boss Harris wants to recruit at least two players next month, but he expects stiff competition from other clubs for targets.
Harris also said "opportunities have run out" for some players in his squad.
"I think January is really up in the air for a lot of clubs," Harris said. "There's going to be a little bit of toing and froing until late on. There will be people thinking if they can get a player in, then they can let another out.
"It's going to be a question of if players are available, are they going to make us better? And will they be available on January the first or the thirty first?
"There are going to be a lot of clubs vying for similar players. Do we need to add to our squad? Yes, to give us that strength and impetus.
"I've given players an opportunity, and another one and another one, but those opportunities have run out. Changes need to be made if we're to progress and kick on.
"We want to carry on building for the future. We don't want to take the opportunity away from our young players, who are good players but are going to be really, really good players. You don't want to take away the opportunity for them to learn, and sometimes playing through sticky spells is the best way.
"But you have to have the balance to be able to take someone out during a tough spell and then put them back in again.
"Sometimes we haven't been able to do that because of a lack of competition. And that doesn't help them.
"Young players often understand that they need to be taken out, but if you don't have someone knocking on the door pushing to go in I can't leave that young player out."