Liverpool's Virgil van Dijk is "probably the best centre half in the world" according to the man who brought him to British football.
Neil Lennon signed the Dutch defender for Celtic in 2013 from Groningen.
Van Dijk, 27, led Liverpool into the last eight of the Champions League, scoring in the victory at Bayern Munich and the Reds will face Porto next.
"He's brilliant. He could walk into any team," said Lennon, who is in his second spell as Celtic manager.
"He's got pace, composure, physicality, technically brilliant. I'm just so surprised none of the real mega clubs didn't take him [from Southampton] before Liverpool did."
"I thought he would be a top, top player but he's made progress very, very quickly. Sometimes they look at the Scottish game and think he's cruising there but can he do it in England? Virgil had all the qualities to do that already.
"One of the best. Value for money, quality, brilliant bit of business by the club."
Van Dijk was spotted by Celtic's former head of talent development John Park, who has been linked with a return to the club amid speculation suggesting current head of recruitment Lee Congerton will take up a similar role at Leicester City alongside former Celtic boss Brendan Rodgers.
"He did alright," said Lennon of Park. "He didn't do badly.
"Lee is here, I'm working with Lee and it's business as usual. I know there's a lot of speculation surrounding Lee. We had a meeting 10 days ago, and he was full on.
"It's a case of maybe watching this space. If he does move on I'm sure there will be a lot of candidates the club have in mind to takeover."