Rolling with the Stones The Black Eyed Peas get frank about Fenway BY MIKAEL WOOD

"Fenway Park?" asks Will.i.am of the Black Eyed Peas, over the phone from Los Angeles. "That’s gonna be stupid!" The rapper/producer thinks for a second, then drops his voice to a conspiratorial whisper. "I’m gonna be so scared."

That’s a fair reaction: though the Peas’ fan base has skyrocketed since the release of their 2003 smash, "Where Is the Love?", when the quartet open for the Rolling Stones at Fenway August 21 and 23, they’ll be playing to a crowd that may not even recognize the infectious hip-pop group from their iPod ads. The Peas are the latest in a long line of important acts the Stones have hand-picked as openers; previous honorees include Living Coloür, Stevie Wonder, and Peter Tosh. Oh, yeah, and the Spin Doctors. Elephunk (A&M), the album that housed "Where Is the Love?", has sold nearly three million copies in the States. Still, Will and his mates — Fergie, Apl.de.ap, and Taboo — have every reason to wonder what to expect at Fenway from 30,000 people waiting impatiently to hear "It’s Only Rock ’n’ Roll (But I Like It)."

It won’t be the first time. For their first two albums — 1998’s Behind the Front and 2000’s Bridging the Gap (both Interscope) — the Peas were known as part of LA’s "conscious hip-hop" scene, along with Ozomatli and the Jurassic 5. They were well intentioned but dead boring as they tried to bridge the gap between neo-traditionalist hip-hop fans and mainstream radio. So when Elephunk, an exuberant, funk-inflected fusion of rap, rock, and pop, connected with Top 40 listeners, there was much speculation about the band’s "artistic integrity."

"People say, ‘Oh, Black Eyed Peas, you ain’t what you used to be on your first record,’" acknowledges Will (born William Adams). "Aesthetically and subconsciously, I don’t see a difference because we’re in it. But the competitiveness in me says, ‘Well, how about this joint?’ We have a song called ‘Like That’ on our new record that sounds like it could have been on our first record."

That new album is Monkey Business (A&M), and like Elephunk, it finds the Peas in evolutionary mode. "Like That" wouldn’t have been out of place on Behind the Front: laced with guest verses from Q-Tip, Talib Kweli, and Cee-Lo, it layers straightforward rapping over an Astrud Gilberto string sample and a stripped-down boom-bap beat. But the rest of Monkey Business is easier to distinguish from BEP’s earlier, more reserved material: "Pump It" is a shamelessly playful refashioning of Dick Dale’s "Misirlou"; lead single "Don’t Phunk with My Heart" is a dizzy Bollywood synth-pop rave-up; "My Style," with another Justin Timberlake cameo, rides a throbbing Timbaland beat; "Don’t Lie" is a breezy ballad with strings and a big vocal turn by Fergie, a former member (as Stacy Ferguson) of the also-ran pop trio Wild Orchid who joined the Peas right before Elephunk. The music on Monkey Business may be lightweight, but that’s not a bad thing. Behind the Front was lightweight too — just in a less interesting way.

On its cover, the July issue of Vibe promised to answer the burning question "Why hip-hop loves to hate the Black Eyed Peas." Will’s response: "I care but I don’t, all at the same time. I care because it’s like, ‘Wait a second, I haven’t changed. I still like the same type of shit.’ My equipment’s changed. Maybe they’re talking about the fine-tuning and the cleanliness . . . everything sounding pristine and punchy. But then there’s a part of me that goes, ‘Really?’ Me as an MC in 1998, how would I feel about myself in 2005? Would I try to battle me? Would I think I’m wack? So I battle me. I sit in the studio and battle the rapper that I was in ’98."

What does the rapper who wouldn’t have dreamed of opening for the Rolling Stones in ’98 think of the rapper who’s about to do just that in 2005? "If somebody had said ‘Where Is the Love?’ is the song people are gonna remember you by when we started the group, I’d still want to be in the group. I’d be happy as shit."

Rolling Stones + Black Eyed Peas | Fenway Park, Boston | Aug 21 + 23 | 617.228.6000