Rihanna sexy bikini Instagram PHOTOS: move over Chris Brown, RiRi 'crushes' on Tom Hardy and Mychal Kendricks, Karrueche Tran has nothing to worry about!

It's Friday - so that means it's time to celebrate the weekend with some sexy Rihanna Instagram snapshots!

This time, RiRi poses in a skimpy black bikini in Brazil... and once again, she's gorgeous!

badgalriri: "#brazil #iloveyou." 

Stunning.

But Karrueche Tran really has nothing to worry about... it doesn't look like Rihanna wants to "win back" Chris Brown anytime soon. In fact, she has a slew of Instagram "man crushes" to choose from! As Mstars previously reported, the songstress has the major hots for actor Tom Hardy and NFL star Mychal Kendricks:

Rihanna is taking part in Instagram's "Man Crush Mondays." So, who's the lucky guy this week?

Popular English actor, Tom Hardy!

badgalriri: "Whoa it's almost Tuesday.... #MCM #tomhardy."

Unfortunately, the 36-year-old "Dark Knight Rises" hunk already has a serious girlfriend - actree Charlotte Riley. In fact, the couple got engaged back in 2010. Hey, RiRi can still have an innocent crush on the Hollywood hottie, right!?

Last week, the "Stay" songstress' MCM was NFL superstar Mychal Kendricks. Several fans refer to the Philadelphia Eagles linebacker as a Chris Brown lookalike - but with more muscles:

badgalriri: "Is it Monday? Cuz chhh.... #MCM."

Of course, this immediately ignited rumors that the two were dating. But that remains unconfirmed.

Which heartthrob will be RiRi's top choice next week?

Do Mstars fans think RiRi will snatch one of her crushes soon? With these sexy photos, probably!