Monaco head coach Leonardo Jardim has warned his underperforming players some of them will need to look for new employment in January.
The defending champions lie third in Ligue 1 behind Lyon and runaway leaders Paris Saint-Germain and finished bottom of Champions League Group G with just two points as Besiktas and Porto qualified for the last 16.
Following his side's final European action of the season on Wednesday night, Jardim is already making plans for a reduced workload.
"We only have three competitions now and we will need to reduce the squad," he told L'Equipe. "Monaco have never had a big winter transfer window while I've been here.
"Some will need to play elsewhere. The priority is to reduce the group, more than bringing in players.
"When you close up the group, everyone is more focused. I will have 18 players with me, plus one or two youngsters, and that will be good.
"When you have 25 players, you always leave 14 of them out of the team. That is not good for the club or the players as our aim is for them to progress."
Jardim rotated his squad for the final Champions League group game but Monaco were well beaten, with Porto winning 5-2.
Rachid Ghezzal was sent off before half-time, along with Porto's Felipe, and it took a penalty converted by defender Kamil Glik and the introduction of striker Radamel Falcao to get them on the scoresheet after they trailed 3-0 and 4-1.
Jardim said: "The players who played gave everything but it did not work. We made a lot of mistakes and at this level you pay dearly for them."
"That is perhaps why they play less. I am not in the habit of playing the players who are performing less well, I always play those who are in the best form."
Monaco won Ligue 1 for the first time since 2000 last season but stars including Benjamin Mendy, Bernardo Silva, Tiemoue Bakayoko and Kylian Mbappe were allowed to leave in the summer.