Alexander Skarsgård says he admired Rihanna for her work ethic while filming their movie, Battleship. The True Blood star thought he had a hectic schedule but it was nothing compared to the Barbadian singer who juggled her music commitments while filming the action flick. Alexander told Bullett magazine that Rihanna was adept at multi-tasking and was in good spirits while doing it. \"God, I thought I worked a lot,\" he said of the Umbrella starlet. \"We would shoot until late Friday night and she would jump on a plane and go to L.A. to perform at the MTV Video Music Awards in front of a billion people, and then get straight back on the plane and fly to Hawaii, and go to set Monday morning with a smile on her face.\" However, Rihanna\'s busy lifestyle has not been without repercussions as she recently ended up in the hospital suffering from \"exhaustion.\" Rihanna told E! News that she \"had the flu\" but \"never gave myself the chance to recover.\"