"A few hours after arriving in Chicago, Jake Bugg sits backstage and smokes a Marlboro. He's running on one hour of sleep, but based on a rousing 45-minute set to a thousand-plus Lollapalooza sidestage crowd, you'd hardly know it. Now here he is, ruminating on the difficulties of assessing his fame in the Internet era. "I'm not able to grasp concepts of how established I am in certain parts of the world," the 19-year-old native of Nottingham confesses. "I mean, today I was baffled, man. I never thought there'd be that many people here. I was expecting, like, 50 people. Or not even that." Bugg is greatly underestimating his Stateside popularity: since the release of his debut album this spring – a finely crafted batch of foot-stomping folk-rock that went Number One in his native U.K., drawing from The Freewheelin' Bob Dylan, the Everly Brothers and Johnny Cash – Bugg has been touted as one of the best new singer-songwriters of his generation. The model-dating teenager, wearing a black leather jacket in spite of the 80-degree heat, can accept the fact that he has a knack for songwriting. Still, he shrugs it off. "It's just about making music, man," he says, drily. Best Albums of 2013, So Far: Jake Bugg, 'Jake Bugg' Sure. But Bugg, born Jacob Kennedy, is quite good – and fast – at doing so. He revelead to Rolling Stone that he's already nearly finished recording his second full-length album, the bulk of which he recently laid down at producer Rick Rubin's Shangri-la studio in Malibu with a batch of seasoned musicians, including Red Hot Chili Peppers drummer Chad Smith. "That was great for me, to play with some more experienced cats," he says. While in Malibu, Bugg knocked out 12 song despite the fact that he and Rubin had initially only planned to tackle two cuts together. Later this month, following tour dates in Japan and Europe, Bugg will be back in the States, and he plans to finish his as-yet-untitled album in time to release it by year's end. Bugg cherished being able to bounce ideas off Rubin. "That's why Rick's so good," he says. "Because I'll take some ideas to him and he'll be like, 'Why don't you repeat that line?' As an artist you can get quite defensive about your work. But it never feels like Rick's imposing on that. He likes to try and get the best out of an artist." Before meeting the mega-producer, Bugg knew little of his past work. "To me he was just this guy with a beard," he says. "So in a way, I was just playing songs for him." In fact, one of the only recent experiences that's made Bugg stop in his tracks is when he recorded at Sun Studios on a recent trip to Memphis. "I just stood there thinking, 'Johnny Cash has stood here and he did the same thing [as me],'" Bugg recalls. "It's just mad." Is there any worry he's putting out new music too soon after his debut? "I don't really see any harm in it," he says. "It seems like the right thing to do. Might as well keep up the momentum, you know? In this time that I've been touring and traveling the world I had a lot of new experiences and opportunity. Why not write about it?" Bugg has been road-testing some of his new material. During his Sunday set at Lollapalooza, he played a pair of new tunes, including "Slumville," anchored by a seriously bluesy riff and featuring manic, scattershot vocals, as well as "They Won't Catch You and Me," a back-porch stomper that finds the singer offering a plaintive plea to a lost lover ("Please don't leave/I won't know what to do"). He tells us he also debuted a new acoustic song the night before, but admits he still hasn't come up with a title for it. Seeing as he can't legally drink at any of his gigs, Bugg views touring America as something of a body cleanse. "It's good for me," he says. "I come here and I've got a clear head. It's a time for me to detox and just play some music.""