Motherwell have warned Celtic they will have to dig deeper if they want to sign goalkeeper Trevor Carson before the transfer window closes.

The Fir Park side rejected a £200,000 offer on Monday but STV understands Celtic are expected to return with a second bid on Tuesday.

The club are looking to bring in a shot-stopped before Wednesday's midnight deadline after number one Craig Gordon was ruled out for 12 weeks with a knee injury.

Well boss Stephen Robinson admits it would be a "nightmare scenario" to lose Carson so close to the window shutting but insists the 29-year-old will be be going nowhere unless Celtic dramatically increase their offer.

"I spoke to Brendan [Rodgers] yesterday after he had the courtesy to ring me," he explained. "We then passed it over to the money men, Alan Burrows and Peter Lawwell.

"They had a chat but realised our valuations were miles away from one another. That's as far as it has gone at the minute.

"Trevor is a Motherwell player and will stay a Motherwell player until our valuations are met.

"He is very much committed to Motherwell. He has two-and-a-half years left on his contract and it's 24 hours left until the close of the window, so people will be sold from this football club at the right price when we decide, not when others decide."

Robinson stressed how vital the timing of the possible deal could be, hinting he may have let the goalkeeper go for less had Gordon's injury occurred earlier in the month.

"It would certainly make things very difficult for me [if Celtic did meet Carson's valuation]," Robinson continued.

"Player's valuations go up and down depending on what point in the window you're at because the closer you are to the end then the timescale to replace them becomes very difficult.

"So it would have to be a very good bid for us to let Trevor go. It would be the nightmare scenario if we had to let him go now.

"However, we always have things that we can do. Whether you can do that in 24 hours remains to be seen and hopefully we won't have to do that."