Rihanna has been accused of lip syncing at her recent Singapore concert which has caused fans to send out hateful and disappointed tweets at the "Diamond" singer.

"SPOILER ALERT: Rihanna is lip-syncing, from the ex-soundman next to me. Plus red light isn't on, on her mic. She walks like Rihannat though", posted iamcolleen in Twitter account on September 24.

"Had high hopes for #Rihanna tonight but she was absolutely awful!!! #SingaporeGP", tweeted georgiekitch

"Rihanna is lip syncing plus she's late! #wtf." tweeted patolaaaaa

"Rihanna must have been going for the world record of how little she can sing in her live performance at the Singapore f1 concert." Tweeted @JFVDenning,

According to her fans who were present in the concert, Rihanna was not only lip-synching but also looked as if she was on drugs.

"Rihanna looked ratchet as hell, she can't dance and I swear she looks drunk or high on some drugs on stage the whole time." @ievandarwin wrote in his Twitter account on September 24

Is Rihhana's concert behaviour some kind of message to Chris Brown? Chris Brown has gone exclusive with Karrueche Tran. In fact, Brown has even confessed that he is in love with Tran. Would this be the reason why Chris won't ever get back with RiRi? Also, could this be the reason as to why RiRi is emotionally damaged and relying on drugs?

Drake who was allegedly dating RiRi has also revealed on The Ellen DeGeneres Show, that Rihanna is great girl and they had a moment.

"Always support and have love for her ... but I'm not into do-overs. In any regard ... which is an ironic thing to say."

On September 23 Drake went air on 'Chelsea Lately. During the show, Drake talked about his relationship with Rihanna which was quite complicated. According to Drake, Rihanna would always ask about Drake's past "flings" and accused him of looking around for suitable replacements.

Thanks to that, RiRi had lost both potential lovers. Could this be the rational explanation behind her high and rude performances as of late?