Carlos Carvalhal is determined to hold onto star defender Alfie Mawson, suggesting Swansea would only consider selling the England Under-21 defender if they received an offer in the region of £50 million.
Mawson has been heavily linked with Watford and West Ham in the January transfer window, while Celtic and Everton are also reportedly interested in the 23-year-old.
Swansea signed Mawson from Barnsley for £5m in August 2016 and he has two-and-a-half-years left on his contract at the Liberty Stadium.
But Carvalhal insists buying rather than selling is on the agenda of the Premier League's bottom club this month, and that chairman Huw Jenkins has given him assurances that Mawson will not be leaving the club.
"When I signed [as manager last month] it was very clear we would try and bring in players to improve the team,'' he said.
"We will not sell the best players in January, the message is clear.
"I have had guarantees from the chairman, but it depends if someone comes in and gives £50m, £100m, £250m.
"Of course, then it is completely different -- to me, [Philippe] Coutinho or Neymar.
"You can never say that it will not happen, but the fundamental idea is not to sell players and try to improve the team.''
Carvalhal used a fishing analogy last week when he suggested Swansea would have to buy "sardines and not lobster'' in January.
If that was a sign that Swansea will not be spending millions in their attempt to escape relegation, Carvalhal said the club have been busy in their pursuit of targets.
Keeping the fishing talk going, he said: "The boat is on the sea -- but the fish didn't bite the hook.
"There is nothing so far, but you never know when the boat is on the sea.
"It depends if you have a storm or whether the fish are sleeping or not if they come to the boat or not.
"I won't talk about numbers but I want quality players. If we bring some quality players in, it will be on our budget.''
Swansea travel to Newcastle on Saturday with doubts over Renato Sanches and Tammy Abraham.
However, South Korea midfielder Ki Sung-yueng could return after a month out with a calf injury.
"The team against Watford, Tottenham and Wolves played like I want at that moment,'' Carvalhal said about his first three games in charge.
"Let's see game by game. It is not just the philosophy, it is trying to achieve points.
"It will not happen in two days or two weeks.
"It might not be possible for the team to play as I want after just a month, what is important is that we fight to win games.''