Robert Downey Jr. was "grumpy" when he first started shooting 'Sherlock Holmes: A Game of Shadows'.

The 46-year-old actor - who reprises his role as Arthur Conan Doyle's legendary detective in the second film in the franchise - enjoyed the "brutal" schedule of the first movie, and was disappointed the action shots were left to the end in the second instalment.

He told Empire magazine: "We had a brutal schedule last time, but it was so much fun, and we were kind of wondering if we could catch this thing on fire and make it work. And pretty early on we figured we were on to something. That is was an ass-kicker.

"And this time around, we only really started the action last week, which had me a little grumpy for a minute."

Director Guy Ritchie accepts there was a "lot of wafflage" in the early days of the filming, while Robert's co-star Jude Law - who plays Holmes' sidekick Dr. Watson - admits the shooting schedule on the sequel was entirely different to the first film.

Guy said: "We shot a lot of waffle straight away. There was a lot of wafflage."

Jude added: "It's been completely the other way round this time. The first time, we got into the action from the get go, and at the end we were in New York shooting all the interiors. This time we were in Baker Street from day one.

"We're joining dots."

'Sherlock Holmes: A Game of Shadows' is due to be released in December.