Gylfi Sigurdsson is likely to join Everton, according to Swansea captain Leon Britton, who has told BBC Sport the club must try to replace him with someone of the same quality.
The Iceland international played a key role as Swansea avoided relegation from the Premier League, scoring 11 goals and setting up a further three, form that has caught the attention of Everton.
The clubs are yet to agree a fee with Swansea wanting £50m but Everton having reportedly bid only £40m. However, Britton believes there will be some movement and the move will happen.
"He will be a massive loss," he said. "When you see his stats last years in terms of assists and goals you would be thinking he would definitely be playing for one of the teams in the top half of the table.
"He's a big influence in the top end of the pitch for us but unfortunately at the club we're at, Swansea, when someone does so well like that the bigger teams come calling and it is hard to keep him.
"In one way the club has stood firm. By all accounts they want £50m. I don't know if it is going to get done. I think Everton have offered £40m or £45m so I think there will be some movement there and maybe Gylfi will go.
"If he does go it is vitally important that we replace him with the same quality as much as we can really."
Sigurdsson missed Swansea's preseason tour of the United States and also the friendly against Birmingham and Britton said it is in the best interests of the club and player for a resolution to be found as quickly as possible.
"It has maybe dragged on a bit longer than a lot of people have expected," he said. "Gylfi didn't travel to America, he didn't travel with the squad at the weekend for the friendly against Birmingham away so when things like that happen you do think that the transfer will happen but you never know, things could change overnight.
"Maybe Everton could decide they don't want to pay that money for whatever reason or a new target becomes available that they think might offer better value for money so you do live in hope that he will stay.
"But Everton have bid a lot of money before and they are not too far away from [his reported asking price] and they might come back through with it...
"It would be better if it could be done either way and put to bed, whether Gylfi was to leave or Gylfi was to stay.
"For Gylfi as a friend and a teammate I wouldn't want it to drag on and on and I think it would be better for all parties if a decision could be made either way. I think there probably is a little bit of frustration there that he wants it done."