The Reds are set to face the Primeira Liga side in the second leg of the quarter-final on Wednesday, and Klopp was full of praise for the 22-year-old striker - but not just for his footballing talent.
The Uruguayan netted his side's only goal in the first leg, capitalising on a defensive error from Liverpool centre-back and opening scorer Ibrahima Konate.
Nunez's goal against the Reds was his 28th goal of the season in all competitions, a tally which has since risen to 31 after hat-trick against Belenenses on Saturday.
With the ability to play on the left wing as well as centrally, Nunez is one of Europe's most coveted goalscorers, and following his side's quarter-final first leg defeat, he has certainly caught the eye of Liverpool boss Jurgen Klopp.
"Extremely good looking boy, huh?" Klopp joked ahead of the Champions League clash.
"And a decent player as well," he added. "Really good, really good. I knew before, of course, but he played pretty much in front of me with his tough battles with Ibrahima Konate.
"He was physically strong, quick, was calm around his finish. Good, really good. I always say in these situations if he is healthy, it's a big career ahead of him."
Nunez is sparking the interest of the Premier League big boys at the right time, with more and more reports linking him to a potential move to England.
It's understood the Uruguay international has garnered the attention of numerous English clubs, including the likes of Manchester United, Arsenal and Manchester City, with each club in search of a striker.
Tottenham and Newcastle have also been linked with the player but West Ham could his destination, talkSPORT were told.