Sterling hit a hat-trick in the second half as City came from behind to win 5-1 at the Etihad Stadium.
Following the victory, Guardiola praised the manner in which his side performed against the Italian outfit, but he reserved special praise for Sterling, per Sky Sports.
"All the credit is for him," the City manager said. "He's a guy whose physicality is incredible, he is so strong. A day after a game, he could play another game. His regeneration is incredible. He can play both sides, he's fast and defensively he helps us a lot. He is an extraordinary player."
A brace from Sergio Aguero put City ahead after Ruslan Malinovskiy had given Atalanta the lead from the penalty spot. In the second half, Sterling's treble took the game away from the Serie A side in spectacular fashion:
The City No. 7 was at the heart of all the team's best attacking play. Squawka Football provided the numbers behind a masterclass from the 24-year-old:
The man himself posted the following on Twitter after the game, joking he should have scored four goals after missing a routine chance late in the game:
Sterling's performance was further evidence of his development during Guardiola's time at the club.
While the England international has always been a threat with the ball at his feet, his production of goals and assists has seen a huge uplift over the past couple of seasons.
Now he regularly finds himself in the optimal position to finish, as he did for his first and third goals against Atalanta. Sterling is also able to commit defenders in one-on-one situations before scoring, as he did for the second.
Per Sky Sports, Sterling now has 16 goals in 17 appearances for club and country in 2019-20. The forward is also getting an appetite for goals in the Champions League, something football writer Daniel Storey noted after Tuesday's hat-trick:
While City have dominated English football under Guardiola for the last couple of campaigns, in the Champions League they've never quite shown their best. In the previous two editions, they've been knocked out at the quarter-final stage.
This season, there'll be a determination to go further, and there's no doubt City have a squad capable of advancing to the final. In Sterling, they also now have one of the most effective forwards in the world.