Last week Italian director Walter Sabatini said the 27-year-old Brazilian was an "excellent" player, but added there was a "distance" between the two clubs regarding a deal.
Initial reports had suggested a €14m (£12.2m) bid from Roma was not seen as satisfactory by the Spanish outfit, leading to speculation Sabatini was trying to sweeten the deal by offering €16m (£14m).
And while the clubs continue to negotiate, Nilmar has expressed his desire to play in Serie A.
"I know Roma and Villarreal are talking and I would be very happy to come to the Italian capital to play football.
"Roma are a great club and I would be playing alongside players like Francesco Totti and Daniele De Rossi."
The Italian club are looking at Nilmar as a replacement for Mirko Vucinic who recently joined Juventus.
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