Werder Bremen are braced for a historic windfall with teenage defender Karim Coulibaly attracting heavy interest from the Premier League. The 18-year-old is expected to command a club-record fee that could reshape the German side's financial future.Bremen are preparing for a seismic summer departure as 18-year-old centre-back Coulibaly emerges as one of Europe’s most wanted defensive prospects. The defender has enjoyed a stunning breakout campaign in the Bundesliga, making 21 appearances and establishing himself as a pillar of the backline at the Weserstadion.According BILD,The Green-Whites will demand a transfer fee of around £42 million, a figure that would shatter their previous transfer record. That benchmark has stood since 2009, when Juventus paid €27m for Brazilian playmaker Diego. With no release clause in his contract - which runs until 2029 - Bremen sit in a dominant negotiating position.The buzz surrounding Coulibaly has reached the boardroom, with Bremen’s sporting lead Clemens Fritz reportedly holding concrete discussions with the player’s representative, Nochi Hamasor. Both parties appear aligned on a summer exit, provided the club's valuation is met by one of the circling Premier League, Serie A or Ligue 1 suitors. However, head coach Daniel Thioune is keen to keep the youngster grounded while his stock continues to rise on the global stage."That's thinking a bit too far ahead for me," said Thioune. "What is best for the club and the player, I do not want to judge that. The fact is that he possesses high quality and is far from the end of his development."While losing a talent of Coulibaly’s calibre represents a significant sporting blow, the economic reality is impossible for the Bundesliga outfit to ignore. A €50m injection would provide a massive financial boost for the club, effectively doubling their record sale and allowing for a comprehensive squad overhaul.Scouts from England’s elite have been frequent visitors to northern Germany this season. They view the former Hamburg youth product as a rare commodity: a teenager with elite physical attributes who is already proven in one of Europe’s big five leagues.Add GOAL.com as a preferred source on Google to see more of our reportingCoulibaly is currently sidelined with a hamstring injury but is expected to return to the squad for the home match against Mainz on March 15. His return will be a welcome boost for Bremen, who are looking to improve their position, as they are currently battling for survival in Germany's top flight.They currently sit 16th in the table with 22 points from 24 matches, just two points above Wolfsburg, who are in the relegation zone. Before facing Mainz next week, Bremen will first face Union Berlin at Alten Forsterei on Sunday.