Thor's Lorelei and Lady Sif are headed to Marvel's Agents of SHIELD, but it is the upcoming Captain America: The Winter Soldier crossover that fans really need to worry about.

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As part of the Marvel Cinematic Universe, Agents of SHIELD sometimes gets fun visits from well-known characters, but it also has the more difficult task of reacting to the events of the franchises major films.

While Thor's Lady Sif (Jaimie Alexander) will chase her seductress nemesis into Midgard during "Yes Men" (see photos above), the Caps sequel will have a more profound impact on the ABC series.

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If you are unfamiliar with the upcoming April release, The Winter Soldier is set to create some major friction between SHIELD and superhero leaders like Captain America (Chris Evans). While Avengers: Age of Ultron will probably show how this affects the world's mightiest heroes, SHIELD will have to explain how the rift will affect the agency's agents.

"If anyone sees a trailer for Captain America, you'll notice that SHIELD is a huge part of what is happening in the movie, just by all the talk of SHIELD and all the SHIELD logos everywhere, so definitely there's a crossover of things happening. I can't tell you how much, but I can tell you that it is insane," said Chloe Bennet (Skye), according to Zap2It. "It will heavily affect our characters, I think. Everyone, definitely go see Captain America 2 and then you're going to definitely want to watch our show before and after."

Find out more when Captain America: The Winter Soldier hit theaters on April 4, and catch Agents of SHIELD ever Tuesday at 8 p.m. ET on ABC. Click the video below to see a preview of the series' next episode, "Yes Men."