They billed it as the “Best of Both Worlds”: The much-hyped concert tour of R’B legend R. Kelly and rap megastar, Jay-Z.

But after a month of missed rehearsals, onstage temper tantrums, canceled concerts, an alleged death threat and an attack that sent Kelly and his bodyguards to the hospital, the tour quickly became the War of the Worlds.

Though only a month long, the war is far from over. Kelly has sued Jay-Z and tour promoter Jeff Sharp, for $75 million. They are set to go at it May 2.

The tour provides a rare terrestrial look at what happens when two stars collide. Both men dominated their genres and the tour was estimated to pull in at least $30 million.

In June 2002, just before the two stars issued their first joint album, “The Best of Both Worlds,” Kelly was indicted on charges of distributing child pornography – a videotape purportedly showing him having sex with a 14-year-old girl.

Jay-Z, who was serving three years’ probation for stabbing a record producer, distanced himself from Kelly. The album tanked.

By November 2003, the relationship began to thaw. Kelly appeared at Madison Square Garden in a sold-out concert celebrating Jay-Z’s short-lived retirement. Soon after, the pair recorded another album together. Its title was auspicious: “Unfinished Business.”

Last July, the two agreed to a tour involving 42 concerts in 39 cities. Kelly was to receive 60 percent of the proceeds with Jay-Z taking 40 percent.

But last November, Kelly’s Manhattan lawyer, Edward Hayes, filed a lawsuit against Jay-Z and promoter Sharp, charging that the rapper “sabotaged” the tour to “elevate his own status and to retaliate for having to agree to a lesser share of the tour revenues.”

Jay-Z’s lawyer, Jonathan Davis, scoffed at the suit. “A calculated stunt to deflect public and media attention from his upcoming felony trial,” he called it.

Hayes maintains Kelly got the lion’s share because of his “greater star status.” Davis contends Jay-Z agreed to the deal only because Kelly complained he “desperately needed money,” apparently for his criminal defense.

If Kelly was worried about his indictment, you wouldn’t have known it from the opening show in Chicago.

At one point, he flashed a fake e-mail message on a giant video screen above the stage saying he was “looking for a girl.” She “must be down for everythin. … She has to be at least 19!”

In another skit, he simulated sex with dancers in a prison cage.

When Chicago reviewers panned the skits, Kelly scrapped them.

Actions such as this and the suits, countersuits and criminal charges will keep lawyers, spin doctors and gossip columnists busy for months.