Advice to Jay-Z: Keep your distance

Though it was titled the “Best of Both Worlds” union between the reigning kings of R&B; and hip-hop, Wednesday’s concert at Allstate Arena brought out some of the worst in R. Kelly. And Jay-Z was at his best only when he kept his distance from Kelly on the opening night of their two-month tour (no California dates have been announced).

Between them, Kelly and Jay-Z have sold more than 40 million albums in the last decade. Kelly’s salacious ballads and exultant gospel-tinged anthems have influenced nearly every successful R&B; singer to emerge after him.

Jay-Z, the Brooklyn rapper, rose from a hardscrabble background to become not only a bestselling artist but also a successful business mogul. As much celebrities as artists, Kelly and Jay-Z dispensed with musical formalities such as a live backing band Wednesday and performed to backing tapes while two tiers of video screens worked overtime to distract from the vast emptiness of the stage.

The concert opened with a simulated crash, as two tour buses broke through a wall and Kelly and Jay-Z emerged. They reprised a handful of songs from their clunky 2002 album, “The Best of Both Worlds,” but they might as well have been in different time zones.

Though their white suits complemented each other, nothing about the performance did: Kelly crooned, Jay-Z fired rhymes, and “Get This Money” and “Somebody’s Girl” sounded more like the product of a shotgun marriage of R&B; and rap than a true collaboration.

If there was a reason these artists were sharing a stage besides money -- promoters estimated that the first two nights of the tour at the Allstate would bring in $1.6 million -- it wasn’t apparent from this performance.

They united to proffer a new single, “Big Chips,” from a forthcoming album, “The Best of Both Worlds: Unfinished Business,” but it didn’t make much of an impression.

Jay-Z played into his ruthless godfather persona, rising from a recliner with cigar clenched between his teeth to dish about “99 Problems” and reprise the rap verses in his 2003 hit with main squeeze Beyonce, “Crazy in Love.”

He rolled out some of his proteges, including the gruff-voiced Freeway and Memphis Bleek, and in black-rimmed glasses delivered raw versions of classic tracks, including “Money Ain’t a Thing,” “Takeover” and “Heart of the City (Ain’t No Love).”

Kelly was splendid when he focused on his best songs: a feisty “Ignition,” the reproachful ballad “When a Woman’s Fed Up,” and a buoyant “Step in the Name of Love” and “Happy People,” with a stage full of stepping dancers accompanying him.

But when the singer addressed his recent legal problems -- he faces 14 charges of child pornography -- things got weird. He made a major error when he placed a text-message want ad for a girlfriend that appeared on the video screens: “She’s got to be at least ... 19 years old.”

The crowd tittered, and then Kelly reemerged in a prison cell simulating sex with two writhing women -- an ill-advised idea for a singer facing a potential prison term.

Later, a handwritten letter appeared on the video screens in which Kelly excoriated former friends for abandoning him and struck self-pitying poses (“so many times I started to quit and walk away from the whole ... thing”). Singing with Jay-Z at his side, Kelly wondered what it would take to “stop people from hatin’ me.”

A few minutes later, he and the rapper clasped hands for the only time all evening, a lukewarm conclusion to this half-baked and self-serving musical summit.