The Liverpool boss is more than wary of the Argentine, whom he called the greatest player ever
Liverpool manager Jurgen Klopp is alert to the danger Lionel Messi poses to his side, with the Argentine's stated desire to win the Champions League a threatening proposition.
Barcelona will host Liverpool in the first leg of a highly anticipated Champions League semi-final on Wednesday.
The Blaugrana had gone out at the quarter-final stage of the Champions League in three consecutive seasons before getting past Manchester United in this year's competition.