Rihanna who? 'Life & Style' has learned that during the 'Saturday Night Live' 40th anniversary after-party, sparks flew between Leonardo DiCaprio and 'Fifty Shades of Grey' actress Dakota Johnson!

During the bash, held at The Plaza Hotel, Leo barely glanced at rumored fling Rihanna. Instead, “he put his arm around Dakota and led her into the grand ballroom,” a partygoer exclusively tells 'Life & Style.' “He told her, ‘Let’s go look at all the celebrities.’”

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Sounds like a line — but it worked! “Dakota looked like she was trying to play it cool, but you could tell she was thrilled to have his attention,” the witness says, adding that “out of everyone he socialized with, Leo seemed to be the happiest when he was with Dakota.”

“As they walked away, Leo took the lead and guided her through the crowd, and a small smile spread across her face.”

For more on Leo and Dakota and all the latest celebrity couple news, pick up the new issue of 'Life & Style,' on newsstands now!