North American/European Tour 2010

Just days after it was announced that Nicki Minaj would be joining Ke$ha as an opening act for Rihanna's Last Girl on Earth Tour this summer, the Young Money rapper has decided to not participate, according to a tweet she posted on Wednesday (April 7).

Late Tuesday, Minaj took to Twitter to hint at the news. "*sighs* how ... how do i say this ... hope the barbz [her fans] will understand ... hate letting them down. *sighs again while in deep thought*," she wrote.

And on Wednesday afternoon, the rapper dropped the news. "Barbz I'm sorry 2 say I will not be going out on RiRi's tour. I've decided 2 use that time 4 the completion of my album. Hope u understand," she tweeted.

A rep for Minaj confirmed to MTV News that the MC is leaving the tour to complete her album.

Minaj's decision to focus on her debut album comes as a bit of a surprise, since she told MTV News in February that she wasn't in a rush to release the album because she felt people need to get used to seeing a female rapper again.

"With the album, just like with my mixtape, I never like to rush it," she said. "With the album, I think it's more important that people get accustomed to seeing a female rapper again. Before I drop an album, people need to come out and see. People don't even know what a female rapper does."

However, fans can certainly see Minaj in the video for her single "Massive Attack."The clip, which features Amber Rose and producer Sean Garrett, was released last week.

While Minaj's name is still on the tour announcement on Rihanna's official site, it appears likely that the tour will proceed with a new opening act.