Oscar-winning director Danny Boyle was surprised to know that 'Slumdog Millionaire' actors Dev Patel and Freida Pinto were dating, as he had no hint about an impending romance while shooting for the film.

The director had no clue Patel and Pinto are together because he didn't notice any sparks between the pair on the movie set, as reported.

The two actors met while filming the Oscar-winning picture, but spent months denying rumours of a real-life romance before finally going public with their relationship this summer.

The British filmmaker, who spent months directing the pair, admits he had no idea that the onscreen romance between them would spill onto the real lives of the actors.

"I was a bit surprised at first, but then those things tend to pass me by!... I'm delighted for them, they seem to be real soulmates and I'm sure more than that. I'm very happy for them - it seems lovely," said Boyle.

The director has once again teamed up with the creative team of 'Slumdog Millionaire' to make a film on mountaineer Aron Ralston.