Coutinho joined the German champions on a season-long loan deal from Barcelona earlier last week and made his debut as Bayern beat Schalke 3-0 over the weekend.
Lewandowski had previously vented his frustrations at Bayern Munich’s lack of signings in the transfer window after losing valuable experience in the likes of Franck Ribery, Arjen Robben, Matts Hummels, James Rodriguez and Rafinha in the off-season.
However, the arrivals of Coutinho and Ivan Perisic, adding to the earlier captures of Benjamin Pavard and Lucas Hernandez has appeased Lewandowski, who has begun the season in style with five goals in two games.
Dortmund, who have won their opening two Bundesliga games and lead Bayern by two points, added the likes of Thorgan Hazard, Nico Schulz, Matts Hummels and Julian Brandt to their ranks over the summer but Lewandowski insists the Bavarians have better quality with Coutinho in their ranks.
"Dortmund did a lot [in the summer window], they have a big squad. But in the end it's not about quantity, but about quality," he told Sport Bild.
"And from that point of view it's clear to me that we have the players of higher quality."
"His [Coutinho's] final ball is insane, he can be the key in important games, especially in the Champions League. He can give us that something special. It makes us more unpredictable [with Coutinho in the team], which makes us more dangerous."