Rihanna reportedly missed her court deposition because she stayed up all night watching basketball.

The 25-year-old singer has been accused of missing five pre-trial interviews as part of her lawsuit against Berdon LLP of New York and two of its ex-employees for negligence, which she claims resulted in her losing millions of dollars.

Rihanna most recently cancelled a meeting scheduled for June 19 in London because she claimed she was too ill to talk, but it has now emerged she was up until the early hours of the morning, watching her favourite basketball team, Miami Heat, emerge victorious in the 2013 NBA Championships.

At about 4.15am London time, Rihanna tweeted ''#KINGJAMES'' in reference to the team's LeBron James.

She then retweeted a statement saying, ''Big up yaself bosh,'' in support of player Chris Bosh.

According to the New York Post, Berdon LLP attorneys wrote to Judge Kevin Castel in a court filing: ''There is ample reason to believe [Rihanna's] illness was a pretext . . . Internet research reflects that she sent out a 'tweet' at approximately 5am London time.

''The only reasonable conclusion to reach is that (a) [Rihanna] was tired the morning of June 19, having stayed up all night, and did not want to be bothered with a deposition; or (b) this case simply is not enough of a priority for her to comply with the orders.''

The law firm is especially angry since they claim they spent $100,000 to pander to Rihanna's needs by setting up a deposition in London as she was performing on her 'Diamonds' world tour there at the time.

Rihanna's lawyer, Edward Estrada, said in court on Friday (12.07.13) he ''has not looked'' at her Twitter account and she could have simply woken up to tweet, or maybe ''someone else handles her Twitter account.''

A deposition has been ordered for August and Estrada said he would consider dismissing the case if Rihanna misses another hearing.

The pop star has been ordered to pay $100,000 to compensate travel expenses and lawyers fees for both sides.