(Cover) - EN Showbiz - Natalie Portman has sparked speculation she may have had a breast augmentation after wowing onlookers with a seemingly fuller cleavage.

The actress was filming scenes for a new Terrence Malick film at a college game of American football, when audience members noticed her at the sidelines.

The Black Swan star looked gorgeous in a sexy embroidered vest top and black leather jacket, with her newly dyed blonde hair falling over her shoulders. However, it was her impressive dcolletage that distracted fans from the game.

"All eyes were on the 31-year-old as she mingled with actor Michael Fassbender showing off a bulging cleavage," British newspaper The Sun reports. "Natalie's fans aren't convinced her new look is natural. After spotting her at the game, Twitter users logged on to share their views on her curvy new shape. One wrote, Natalie Portman @ the Texas-Baylor game....boob job? Looks like it!'."

Natalie is known for her petite figure, but it was reported that breastfeeding her son Aleph, born in June 2011, gave her a fuller cleavage.

Now the impressive curves she flaunted on set have even caused speculation she may be pregnant again.

"Wait a second, did natalie portman get a boob job? Is she pregnant? On the sidelines of Texas game and #wow, (sic)" another Twitter user commented. (C) Cover Media