Belgian Pro League side KRC Genk want a decision on the future of Championship target Jelle Vossen by the end of the day.
Vossen spent last season on loan with Middlesbrough and has already stated that he would like to return to Teesside, while Sheffield Wednesday and Celtic are also thought to be keeping tabs on the 12-cap Belgium forward.
Genk boss Peter Maes has admitted that he does not expect Vossen to stay with the club this summer, but has also offered the 26-year-old a new long-term contract - but is beginning to lose patience with British clubs showing wavering interest in the former club captain.
Vossen is only a secondary target for Boro
Middlesbrough boss Aitor Karanka is still thought to be undecided on a potential return for Vossen, who scored nine goals last season, and is pursuing other, as yet unnamed, targets first.
Should Boro have enough left in the bank to bring Vossen in, a return would be a popular move among the club's fans; however, a price tag thought to be around £2.2million could be a potential stumbling block as Karanka looks to completely rebuild his frontline after the departures of Vossen and fellow loan star Patrick Bamford.
Genk are desperate to keep Vossen
And Genk technical director Dimitri de Conte says that the club is "pulling out all the stops" to ensure Vossen stays in Belgium, where he has scored 105 goals in 244 league games for the club.
De Conte continued to say that player and agent have agreed to a meeting with the intention of deciding the player's future for sure - after that, he says, it will become apparent which clubs have a "concrete interest" in taking Vossen in.
Though managerless Sheffield Wednesday are monitoring the player's situation at Genk, but should Boro pull out of the race for his signature, Glasgow is thought to be his preferred destination.
Deila looks to rebuild
After bringing in defender Dedryck Boyata from Premier League giants Manchester City, Celtic boss Ronny Deila is another manager looking to strengthen his attack with Vossen high on his shortlist.
Celtic flop Amino Balde is thought to be on his way out of Celtic Park to Ligue 2 side Metz, and Vossen has admitted that the SPL champions are a side he "admires".
Away from Britain, Genk's Belgian rivals Club Brugge are said to be interested in Vossen, who has scored two goals for his country, both in qualifying for Euro 2012.