city rivals Valencia CF, managed by his former United teammate Gary Neville. On 8 May, he scored a late winner in a 2–1 home win over title contenders Atlético Madrid, although the result was not sufficient to prevent the team from being relegated. Loan to Celta Vigo On 29 August 2016, Rossi signed a one-year contract with Celta de Vigo, with an option for another year. He scored his first goal for the club on his debut, which came in a 1–1 away draw against Standard Liège in Celta's opening group match of the Europa League. He made his league debut with the club on 18 September, coming on as a substitute in a 0–0 away draw against Osasuna. On 3 April 2017, Rossi scored a hat-trick in a 3–1 home win over Las Palmas in La Liga; this was his first goal since he scored against Espanyol on 25 September 2016, and his first hat-trick since 20 October 2013, when he scored three goals for Fiorentina in a 4–2 home win against Juventus. On 9 April 2017, Rossi suffered the fifth serious injury of his career when he ruptured the ACL in his left knee in a game against SD Eibar, and was consequently ruled out of action for at least 6 months. Rossi became a free agent in July after Fiorentina allowed his contract to expire and he subsequently rejected an offer by Celta to remain with the Spanish side until January 2018. Genoa On 4 December 2017, Rossi was signed by Genoa on a free transfer. He made his debut for the club on 20 December, coming on as a second-half substitute in a 2–0 away defeat against Juventus in the round of 16 of the Coppa Italia. He left Genoa at the end of the 2017–18 season. On 12 May 2018 Rossi failed a drug test following a Serie A match against Benevento, testing positive for the banned substance dorzolamide. Although the country's anti-doping prosecutor wanted Rossi to face a one-year ban for this offence, following a hearing with that took place on 1 October, Rossi was ultimately given a warning; afterward, Rossi's lawyer Sergio Puglisi claimed: "We don't understand how this substance ended up among Rossi's foods, there was no intentionality – the line of good faith and consistency prevailed." Rossi later tweeted: "A nightmare of four months is over. I only want to think