Robert Downey Jr. has already expressed his interest to star in an "Iron Man 4" film. Now, the actor has made an intriguing suggestion as to which director is best to helm the movie.

"I think he wants Mel Gibson to direct it," Shane Black, who directed the third "Iron Man" film, revealed to Uproxx. "And for good reason. Mel was great to him. Mel's been really nice to a lot of people, including me," the filmmaker added.

"Yeah, one of these days, maybe Downey will do another one. I'd love to work with Robert again," Black said of the possibility of "Iron Man 4" with Downey at the center and Gibson helming behind the camera.

Downey hasn't said anything much about "Iron Man 4" except that he "feels" he could do one more "Iron Man" movie. Nothing is made official yet although Downey's days as Iron Man see no end yet.

The actor will play the character in upcoming Marvel movies, including the two parts of "Avengers: Infinity War" and "Spider-Man: Homecoming." Whether or not an Iron Man solo film will be in the works, it is unclear for now.

However, in the event there will be, fans hope that Tony Stark's girlfriend Pepper Potts played by Gwyneth Paltrow will be back. In "Captain America: Civil War," it was hinted that her and Tony are not together.

According to Movie Pilot, Pepper Potts presents an interesting story for "Iron Man 4." At one point in the comics, she also took on superhero duties like Iron Man. Tony designed a suit for her, and she went by the superhero name Rescue.

It will definitely be interesting to see that unfold in "Iron Man 4." However, unless it isn't official, fans will have play the waiting game and for now, hope this happens in the big screen in the future.