While most new parents are desperate to catch up on lost sleep, Jay-Z and Beyoncé Knowles were spotted partying and singing duets together in a Paris nightclub, according to reports.

The couple were in the French capital as part of Jay-Z and Kanye West’s Watch The Throne concert series, and were photographed at a star-studded after party at Parisian hot spot L’arc alongside their actor pal Adrien Brody, who co-starred with Beyoncé in the 2008 movie Cadillac Records.

To the surprise and delight of onlookers – including tennis star Serena Williams, producer Quincy Jones and Whitney Houston’s former mentor Clive Davis – Jay-Z and Beyoncé once reportedly belted out the lyrics to Houston’s classic hit I Will Always Love You when the DJ played it in tribute to the late singer.

"Jay and Beyoncé don't usually do that kind of thing, the rest of the party couldn't believe it," a source told British newspaper The Sun.

Earlier, Beyoncé, who gave birth to baby Blue Ivy in January, had been cheering on her husband at the Palais Omnisports de Paris-Bercy. The 30-year-old singer was joined by celebrity girl friends Gwyneth Paltrow and former Destiny’s Child bandmate Kelly Rowland.

The three-hour set saw Jay-Z and West set the arena on fire by performing N***** In Paris a record 11 times. The hip-hop stars have ended previous Watch The Throne shows with consecutive performances of their smash hit, but this time they broke their own record with a remix lasting more than 45 minutes.

Movie director Spike Lee and pop star Justin Bieber were also in attendance with both tweeting about the show. Lee wrote: "Record Was Broken Tonight.11 Encores Of N****'s In Paris-IN PARIS."