Idrissa Gueye will always have September 18, 2019.
On that day, the Senegal international made his bow for Paris Saint-Germain in the Champions League and looked like he belonged on that stage. Against no less a side than Real Madrid, Gueye was nigh-on unplayable, and powered the French side to a memorable, richly deserved 3-0 win.
However, a performance that should have served as a springboard has instead proved a high-water mark. His output has steadily declined in the competition since, and against Borussia Dortmund on Tuesday night he looked like he would rather have been somewhere else entirely.