Bayern without Robben for Besiktas - Heynckes
Robben came off the bench in the first leg - a 5-0 thumping of the Turkish champions in Munich - but started and scored in a 6-0 Bundesliga demolition of Hamburg on Saturday.
Bayern's massive advantage ahead of Wednesday's trip to Istanbul gives Heynckes freedom to rest some of his key players, with Robben set to sit the game out.
"James [Rodriguez] is training with the team recently, but of course he's an option, just like Thiago," Heynckes told reporters.
"And Arjen Robben could have played tomorrow, but I'm careful - he has some complaints."
#Heynckes: "@jamesdrodriguez is an option again, as is @Thiago6. James trained well these last few days." #BJKFCB #packmas pic.twitter.com/iHKqoOs6Kk
— FC Bayern English (@FCBayernEN) March 13, 2018
Robben has started 16 Bundesliga games this season, scoring four goals, as Bayern close in on another title and the 34-year-old, like fellow experienced winger Franck Ribery, is out of contract at the end of the season.
Ribery starred in Bayern's traditional mauling of Hamburg at the Allianz Arena and Heynckes was particularly impressed with the display of the former France international.
"When I came, he was injured and could only work in the gym," Heynckes said. "He returned well prepared in the Bundesliga and has found his rhythm well.
"His performance against Hamburg was exceptional. He is a very important player and will show that in the coming weeks."
"We're preparing for the game as though we are starting at 0-0. We want to be bold and build-on our performance in the first leg." @esmuellert_ #BJKFCB pic.twitter.com/916C7EPBst
— FC Bayern English (@FCBayernEN) March 13, 2018
Heynckes is yet to confirm whether he plans to stay at Bayern beyond the end of the season, having been given a short-term deal when he was appointed following the sacking of Carlo Ancelotti in September, taking charge for the fourth time.
And the 72-year-old, who led Bayern to the treble at the end of his third period in charge, is giving nothing away about his future.
"I'm not ready to interpret the statements of [president] Uli Hoeness and [chief executive] Karl-Heinz Rummenigge again and again," said Heynckes.
"I know what I want, you have to wait until the decision is announced."