Rapper Kanye West is winning the chart battle with 50 Cent on both sides of the Atlantic, early sales figures show.
Kanye West's song Stronger has been a major hit
West's Graduation, which was released on the same day as his rival's third album, Curtis, could top the charts in both the UK and US.
50 Cent, real name Curtis Jackson, has vowed that he will retire from making solo albums if he is outsold by West.
According to record sales executives in the US, West's album is projected to shift up to 700,000 copies this week.
Meanwhile, West has said that Britney Spears' comeback performance was used as a ratings ploy by MTV.
The musician told a radio station in the US: "Man, they were trying to get ratings. They knew she wasn't ready and they exploited her."
The rapper added that he should have opened the MTV Music Video Awards show with his hit Stronger.
Spears' first performance in three years kicked off the Las Vegas event and was widely seen as a disaster.
West, 30, told Sirius Satellite Radio's Morning Mash Up show that MTV's decision was "a bad move".
"They exploited her, they played me and I really don't mess with MTV," said the chart-topper, who added that he had been asked to perform in a suite instead of the opening slot.
At Sunday night's awards ceremony, West threw a tantrum in front of the media after failing to pick up any of the five gongs he had been nominated for.
"That's two years in a row, man... give a black man a chance," West said. "I'm trying hard, man, I have the number one record, man."
On Tuesday, the music broadcaster issued a statement about its "long and collaborative relationship" with the star, adding: "We hope and look forward to continuing that meaningful relationship."
Spears' performance of her new single Gimme More was critically panned.
BBC correspondent David Willis, who witnessed the performance, said she appeared "really out of sorts" and "looked as though she completely lost the art of lip-syncing".