Liverpool head coach Jurgen Klopp's biggest nightmare ahead of his team's crucial 2018-19 UEFA Champions League semi-final tie against Barcelona will be Lionel Messi.
The Argentinian magician has time and again created something out of nothing in crucial European encounters. Messi leads the pack in the goalscorers' chart with 10 goals from seven starts in the Champions League.
Being one of the best in the world, it is not the goalscoring that Liverpool need to worry about. It's his movement, magnetic ball control and vision as well that will give defenders a difficult time.