Liverpool’s fifth straight home Premier League win of the season moved them three points behind leaders Tottenham.
Diaz, 26, who has made 11 appearances this season and scored three goals, did not feature in the squad.
Diogo Jota held aloft Diaz’s number seven shirt after scoring in a tribute to his missing teammate.
“How can you make a football game really important on a day like this? It’s really difficult. I’ve never struggled with that in my life,” Klopp said.
“We heard late last night about it. We spoke to Luis, he wanted to go home. Then we got the news with his mum, which is fantastic, and since then nothing really.”
The Colombian army said in a statement that it had set up roadblocks and deployed two motorised platoons, unmanned aircraft, helicopters and a plane with radar in the search for Luis Manuel Diaz.
Colombian authorities did not provide details about the kidnapping, but media reports said the player’s father and mother, Cilenis Marulanda, were taken on Saturday by armed men on motorcycles at a gas station in their home town of Barrancas, in the northern La Guajira department.
President Gustavo Petro said that Marulanda was rescued in Barrancas hours later.
Colombia is a country just emerging from decades of civil conflict between rival armed groups, with more than 38,000 people kidnapped, mostly for ransom.
Petro, at an event to mark the start of local elections in Bogota, said “all the public forces have been deployed” to find Diaz’s father.
Source: CNA
