The `Diamonds` singer - who reconciled with the `Turn Up The Music` hitmaker earlier this year before announcing their split this month - looked smitten with Chris as they spent Christmas Day (25.12.12) together watching the LA Lakers basketball team in action.
The two could be seen cheering and sipping drinks, with Rihanna occasionally whispering in Chris` ear and while cuddling him.
She was also wearing a gold collar necklace believed to be a gift from Chris, who is still on probation for beating her up in 2009.
According to gossip website TMZ, the two singers had arrived in the same car but entered Staples Center separately, before meeting up again inside.
However, it seems Rihanna still faces competition from Chris` ex-girlfriend Karrueche Tran to fully win his heart and the pair seem to be going to great lengths to outdo each other on social networking sites.
A source told The Sun newspaper: "Rihanna and Karrueche are really fighting over Chris and have been sending each other coded messages online for weeks.
"They hate each other but Chris seems content to carry on with them at the same time. They were competing over Christmas to send Chris the most loved-up messages possible.
"Rihanna may have got Chris on Christmas Day but he sees no reason not to see Karrueche too."
Earlier this month, Rihanna, 24, was left reeling when he was pictured enjoying a meal with Karrueche in Dubai, and she wrote on her Instagram: "Being single sucks. The only thing I get to do anymore is whatever I want to do (sic)."