Ethan Hawke is suffering severe nerves about the upcoming third installment in the Before Sunrise film series as he fears the finale will be a letdown for fans

The Training Day star appeared opposite Julie Delpy in the original 1995 romance, and they reprised their roles for a 2004 follow-up, Before Sunset, which picks up the story nine years later.

The actors were recently rumoured to have shot a third movie, Before Midnight, in secret but Hawke insists the film is still in the planning stages.

He has revealed the project is going well and they hope to have it completed soon, but he worries some fans may be left disappointed because so many devotees have already planned out how they think the movie should end.

Hawke tells Britain's Daily Telegraph newspaper, "The second Julie mentioned at the Sundance (film) festival that we might do another one, it was all over the internet, and people were blogging and writing outlines for what it should be. One of the biggest problems with the third one is it is invariably going to disappoint people... (But) it will serve as a time capsule in the same way the other ones do... I'm so nervous about this new movie. I know what's at stake and it's scary."