James joined Bayern on a two-year deal from Real last summer lacking confidence and fitness, but has rediscovered his best form in Munich.
"James has developed brilliantly this year," Heynckes told media at his pre-match press conference on Tuesday. "He has so much creativity, and I get the impression he feels at home here in Munich now. He's a top player."
#Heynckes: "Our fans love watching @jamesdrodriguez play. He is a key component of the #FCBayern team. He has a lot of imagination and is a top footballer. He has arrived - and is learning German!" #FCBRMA #MiaSanMia pic.twitter.com/j36WoB2X2A— FC Bayern English (@FCBayernEN) April 24, 2018
It's not the first time Heynckes has lavished praise on the 26-year-old Colombia international. Earlier this season, the 72-year-old described him as "a godsend", adding. "at Real he wasn't getting the playing time he deserved."
How times change. A bit-part player at his parent club, James has made 34 appearances in all competitions in his debut season in the red of Bayern, chipping in with six goals and 12 assists.
Watch: All James' Bundesliga goals and assists
"Our fans love watching James play," Heynckes continued. "He is a key component of the Bayern team. He has arrived - and he's learning German. Although, of course, he likes to chat with the Spanish speakers."
Bayern, who have an option to buy James for €42million in summer 2019, have already expressed their wish to make the playmaker's move permanent.
"We have very clear conditions in terms of the contract," club CEO Karl-Heinz Rummenigge stated at the start of Apirl. "We have a two-year loan deal and then a purchase-option of €42 million that we will have to take up."