Barcelona completed the controversial signing of Martin Braithwaite from Leganes after the club WAS granted special dispensation to complete the deal outside of the transfer window.
LaLiga's champion was given permission to sign a forward after injuries to Luis Suarez and Ousmane Dembele left them short of striking options.
Barca confirmed it has met an €18million release clause to bring in the 28 year-old until June 2024, with a buyout clause set at €300million.
Braithwaite has scored six goals in 24 LaLiga appearances for relegation-threatened Leganes this season.
Angel Rodriguez, Willian Jose, Lucas Perez and Loren Moron were said to be the initial candidates, but in the past few days Leganes' Denmark international Braithwaite has seemingly emerged as the most likely option.
Leganes confirmed Barca made contact with the club on Monday but insisted Braithwaite will only leave if his reported €20million release clause is triggered, with Moreno expressing concern after the relegation-threatened side lost another striker in Youssef En-Nesyri to Sevilla last month.
"Yesterday [Monday] afternoon they called and contemplated this situation," Moreno told reporters on Tuesday. "They only made contact once.
"The truth is that we are very worried. After what happened to us with En-Nesyri, now what happens with Braithwaite ... staying in LaLiga gets more complicated every day. In these next hours we will know what happens, yes or no.
"I don't know if anyone will come from Barcelona today. The player has a day off and we have not talked to him.
"I understand why Braithwaite would go to Barca, I would too. But of course, we are not going to negotiate anything. They pay his clause, or he stays at Leganes.
"I can understand that Barca do this if the law allows them to, but I thought that they couldn't sign an active player, only one free agent. I was surprised."
After 24 LaLiga matches this season, Leganes is second-bottom of the table, only ahead of Espanyol on goal difference and two points adrift of Celta Vigo in 17th.