Costa made the summer move to Bavaria from Shakhtar and scored his fifth goal in 20 appearances for the German giants in Tuesday's a 4-0 Champions League win over Olympiacos.
The 25-year-old Brazil international has also racked up an incredible 14 assists for Pep Guardiola's men and Duda Kroeff, who ran Gremio when Costa made his professional breakthrough in this homeland, believes the player is destined for greatness.
"Douglas' way of playing suits the team," he told TZ. "They are both doing each other much good.
"At Bayern, the football played is football for him. The influence of Pep on him is great, no doubt.
"He will improve even further. He is not a superstar like Messi or Ronaldo but he can get at them."