Trailers of the newest incarnation of Tarzan have shown the 'True Blood' actor swinging his way through the Congolese jungle to rescue his beloved Jane from the latest bunch of crooks in their path.

But neither apes nor human foes were the biggest obstacle to Skarsgård, who spent four months in the gym to get in shape for the physically demanding role. Instead, it was a steamy sex scene with leading lady Robbie that unexpectedly proved to be the toughest part of the shooting.

“They're doing this love scene together, and I said [to Robbie], 'Just slap Alex while you're making love, just kind of give him a punch',” director David Yates told Entertainment Weekly.

“It was sort of an earthy, sensual moment of her enjoying sex with Alex, and the only bruise he picked up during the entire shoot was probably that punch from Margot. Which says a lot about her feistiness.”

Born and raised in gender-equal Sweden, Skarsgård told the entertainment magazine that he loved acting against Robbie's Jane, who trailers hint is far from Hollywood's average damsel in distress, waiting for her husband to come to her rescue after she's kidnapped by villain extraordinaire Christoph Waltz.

“It was very important that we didn't want it to feel archaic or dated, where it's like, tough guy has to save the poor girl. You have to feel that she's strong and independent, and when you cast Margot, you'll definitely get that,” said 39-year-old Skarsgård.

“If you enter the jungle with anybody, you want to go with Margot Robbie,” said Yates. “She’s practical, and she’s smart, and she’s resourceful. And she can take care of herself.”

A member of Sweden's most famous acting family (his father, Stellan, has starred in a diverse range of films including 'Good Will Hunting' and 'Pirates of the Caribbean'), Skarsgård got his Hollywood breakthrough in vampire television action drama 'True Blood' in 2008.

Robbie is 25 years old and has previously starred in Australian soap opera 'Neighbours' and 'The Wolf of Wall Street'.

'The Legend of Tarzan' will be released in cinemas on July 1st.