Sevilla have confirmed that Spain's anti-doping agency are investigating reports that Samir Nasri had intravenous treatment at a Los Angeles clinic.
The clinic, Drip Doctors, posted a photo of Nasri on its Facebook and Twitter accounts on Tuesday, saying it had provided him with a drip 'to help keep him hydrated and in top health during his busy soccer season'.
It describes the drip as an infusion to boost the immune system and contains 'high-dose vitamin C, B vitamins, lysine and zinc combined with specially formulated nutrients'.
Intravenous treatments are banned by the World Anti-Doping Authority for measures over 50ml.