RB Leipzig confirmed the 19-year-old had shaken off the infection that delayed his arrival and linked up with the squad, despite reports suggesting Real Madrid had hoped to keep him away from the camp until a transfer agreement was finalised.
The two clubs are in advanced negotiations, with talks described as having gone "very productively" on Tuesday, and according to Sky the total package for Diomande is set to comfortably exceed €120m.
Real Madrid are understood to be pushing to get the winger through a medical as quickly as possible once terms are settled, wary of any delay that could complicate a deal already regarded as one of the most significant of the European summer.
Diomande's rise has been remarkable given he arrived in Leipzig only a year ago as a relative unknown, joining from Leganes for a fee in the region of €20m before breaking through with a string of standout performances in the Bundesliga and further raising his profile with an impressive World Cup for Ivory Coast.
Should the fee eventually agreed land anywhere near the reported figure, Leipzig would be set to make a return of roughly six times what they paid for him just twelve months ago, making it one of the most lucrative pieces of business in the club's history.
The transfer has not been without complications away from the pitch, with a dispute reportedly ongoing between two separate agencies over who holds the rights to represent Diomande, stemming from the change of representation he made after his move to Leipzig.
Should the deal with Real Madrid go through as expected, governing bodies are understood to be likely to examine the situation further given the sums of money involved.
For Real Madrid, meanwhile, the move would mark a significant statement of intent following interest from elsewhere in Europe, with reports suggesting Liverpool, Bayern Munich and Diomande's long-standing preferred destination Paris Saint-Germain had all previously explored a deal before being priced out or overtaken.