At the same time art fair Frieze heats up Randalls Island this week, rival gallerists David Zwirner and Larry Gagosian are launching head-to-head Jeff Koons shows just blocks from each other in Chelsea. Koons — who recently graced New York mag’s cover as “The Most Successful American Artist Since Warhol” — made headlines in December when he announced plans to work with Gagosian competitor Zwirner, sparking speculation he was following high-profile artists Damien Hirst and Yayoi Kusama out Gagosian’s door. A Koons sculpture of Popeye had also been at the heart of a legal fight between Gagosian and collector Ron Perelman. But Koons has not entirely deserted Gagosian, and instead has launched new shows at both galleries. A show of sculptures called “Gazing Ball” at Zwirner opened last night, and spies said that lines snaked out of the gallery and down the block to get in. The show of fragile orbs balancing on classical-looking sculptures were so delicate, “there were up to three security guards around each work of art” said one source. Gagosian’s show of new Koons paintings and sculptures opens today. Both shows run through June 29. Zwirner and Gagosian are both showing at Frieze, too, which has its VIP preview today. No Koons work is in the hip fair, but his influence looms: artist Paul McCarthy’s debuting an 80-foot “balloon dog,” which has yet-to-be seen but has conjured images of Koons’ sculptures of the same name.