Beyonce joined husband Jay-Z to perform at the Finale of the rapper's concert series at the Barclays Center in Brooklyn, New York, on Saturday night, but it wasn't her singing what caught everyone's attention. 

Beyonce rocked the Barclays Center in black leather shorts and a Brooklyn Nets cap with her curly hair loose. The singer performed her hits "Diva" and "Crazy in Love" accompanied by a couple of dancers. But what will most likely become the talk of the night was the moment when Jay-Z gave his wife a playful slap on her rear.

It was while she was performing "Crazy in Love" that Jay-Z came on stage to rap and gave her a playful slap on her behind.

"Of course I had to let BK touch the stage in BK-- well BKC now," Jay-Z joked, referring to his wife's full name Beyonce Knowles.

The even was live streamed on Jay-Z's YouTube channel where more than 50,000 people tuned in.

To close the event tonight, Jay-Z brought Beyonce again to perform with him "Young Forever." This time Beyonce was wearing tight leather pants and a black leather jacket with blue high heels.

The famous couple kissed and hugged before exiting the stage and ending Jay-Z's eight-night run at the new stadium of the Brooklyn Nets.

Jay-Z announced today that he will be releasing an EP of his concert series at the Barclays Center. The album will be titled "Live in Brooklyn," and will be available on October 9 on iTunes.

Watch Jay-Z Spank Beyonce as she Performs "Diva" and "Crazy in Love" at the Barclays Center Below (4:58 mark):

Watch Beyonce Perform 'Young Forever' with Jay-Z Below:

Tags: Jay-Z