The German coach has chosen his favorite among the pair.

Liverpool manager Jurgen Klopp has had his say on the never-ending debate on the subject of whom the greatest-ever player is between Lionel Messi and Cristiano Ronaldo. The German manager and the Reds traveled to Barcelona ahead of their Champions League semi-final first leg encounter.

Liverpool set up the clash by seeing off FC Porto through an emphatic 6-1 aggregate win. Relatively, Barcelona defeated the Reds' Premier League rivals Manchester United with a 4-0 win to progress to the semis.

Lionel Messi has played a key role in the Camp Nou outfit's campaign so far, scoring 10 goals and assisting three in eight matches. As a result, he is still the focal point when it comes to all matters relating to the threat the Catalans possess.

Ahead of Wednesday's clash, Jurgen Klopp was asked for his views on whom he believes the best player is between Lionel Messi and Cristiano Ronaldo. "Messi would be the player at number one. Cristiano Ronaldo is in that for sure but the rest we have to see," he told the press.

"I coached a few good players but they didn't finish their careers yet.

"I didn't see Pele live but there are a lot of good players. Lionel Messi is for me the best."

Regarding Wednesday's test for Liverpool, the German manager added: "Before the press conference it feels like I had 20 interviews: it is not only about Messi but of course it is about him as well.

"Can we concentrate on Messi? In some moments we should. But they have the highest quality team, they are already Spanish champions.

"I would say a draw would not be the worst result in the world, not that we go for it but it would be OK.

"So many people came to Barcelona and had a plan and in the end, they got a proper knock.

"But there were a few who could really cause problems: we saw the game against Real Sociedad and they did well, Levante did well a couple of days ago.

"The better the opponent is, the higher the stakes.

"We will face them still and I am really looking forward to it but it will be a tough job."