Peterborough United boss Darren Ferguson has warned his side that continued poor performances could force him into the transfer market.
Saturday's means Posh are without a win in their last four Championship games.
"I keep getting asked about this transfer window. And I keep saying I don't want to buy anyone," Ferguson told BBC Radio Cambridgeshire.
"Well they need to get their finger out because I'm not accepting some things."
The London Road side, who sit nine points above the drop zone, have made steady progress compared to two seasons ago, when they were relegated to League One as the Championship's bottom club.
But Ferguson is wary of complacency creeping into his squad.
"I think there's been a certain acceptance that 16th is OK. It's not OK for me," he said.
"The players are forcing my hand a little bit but, as I've always said, it's got to be somebody who comes in and makes a real impact.
"We have got the numbers now because Lee Frecklington, Tommy Rowe and Grant McCann are back. So it's got to be somebody who comes and I say, 'I'm playing him every week'. That's not easy to find.
"I think it's up to the players to take responsibility and get their finger out really."
Meanwhile, midfielder George Boyd is expected to be fit for the weekend visit of Portsmouth.
The 26-year-old has been recovering from a blood infection after suffering a gash to his leg in last week's loss at Hull.
"He was in quite a bad way and spent two days in hospital," added Ferguson.
"We did quite well to keep it quiet but he was always going to be out.
"I hear people say George hasn't done this or that but when he doesn't play you notice it."