Reina kept a clean sheet last weekend as Liverpool ran out 4-0 winners at Wigan Athletic.
Agger believes that Reina was brilliant at the DW Stadium and says that the Spanish keeper remains a consistent performer for the Reds.
He told The Mirror: "Pepe was world class against Wigan. He had a few great saves and he deserves a lot of credit for his performance.
"It says it all if you can have a goalkeeper you can rely on at the back, both with the feet and on the line. Against Wigan, he showed the best of himself."
The 30-year-old has been at Anfield since 2005, clocking up more than 380 Liverpool appearances.