playoff rounds of the 2013–14 UEFA Europa League, Muriel scored his first ever European goals, netting twice in a 3–1 victory over Široki Brijeg and in his first league match of the season, scored against reigning Coppa Italia champions, Lazio in a 2–1 loss. His form declined however, as he struggled with weight and injury issues, and over the course of the next season-and-a-half he scored only four goals in 35 league appearances, including a spell without any goals in 11 matches from the start of the 2014–15 Serie A season. He ultimately amassed 15 goals in 57 appearances for the club, before leaving to join Sampdoria in 2015. Sampdoria In spite of his struggles with Udinese, Sampdoria completed the double loan signings of Muriel and teammate Andrea Coda on 22 January 2015, with an obligation to purchase both players at the end of the season for a combined sum of €12m. In terms of the agreement, Muriel signed a contract with Sampdoria until 30 June 2019. He scored four times in 16 appearances during his loan spell before completing a permanent transfer at the end of the season. In his final campaign with the club he recorded a career best return of 11 league goals and five assists, which prompted Sevilla to break their club record to sign him at the end of the season. Sevilla On 11 July 2017, La Liga side Sevilla announced the signing of Muriel for a reported club-record fee €20m, with potential add-ons. He made his debut on 19 August, starting in a 1–1 draw with Espanyol and scored his first goal for the club on 17 September, netting the winner in a 1–0 victory over Girona. Following a disappointing debut campaign, in which he only scored 9 goals in 46 appearances, Muriel found himself behind Wissam Ben Yedder and new club signings André Silva and Quincy Promes in the pecking order for Sevilla the following season. Loan to Fiorentina On 2 January 2019, Muriel returned to Serie A after signing with Fiorentina on loan for the remainder of the season. He scored a hat-trick on his non-competitive debut a week later in a win over Maltese side, Hibernians before making his official debut on 14 January in a 2–0 Coppa Italia win over Torino. He then scored twice on his league debut on 20 January during a 3–3 draw with former club, Sampdoria.