The 24-year-old is approaching the end of his second season in Germany, having moved to the Bundesliga from French outfit Metz.
His progress has been closely monitored by a number of sides, and they are now ready to make their move.
Freiburg would be reluctant sellers, but Diagne is determined to make the most of a golden opportunity.
He claims the likes of Aston Villa, Fulham, Borussia Dortmund, Bordeaux and Rennes are all chasing his signature, and he will make a decision on his future when the summer transfer window opens.
Diagne told RFM: "The club and the coach do not want to let me go but (other) clubs do not want to miss out on me."
One sticking point in any Premier League move for Diagne could be his lack of international experience.
He is yet to be capped by Senegal at senior level and may struggle to obtain a work permit unless he can obtain an EU passport.