 On 23 September 2018, with a goal in a 1–2 defeat to Alanyaspor, Diagne set the record of scoring 8 goals in his first 6 matches in the Süper Lig since the start of the season.He scored a brace in a 2–2 draw with Fenerbahçe.On 22 December, Diagne scored another two goals in a 4–1 win over Beşiktaş, but was suspended for one league game due to receiving his fourth yellow card.