When the German summer offensive of 1942 began, part of 16th Guards Fighter Aviation Regiment had been re-equipped with the Yakovlev Yak-1 fighter, including Pokryshkin's squadron. In that period Pokryshkin flew missions escorting Su-2 and Il-2 Shturmovik aircraft, and frequently was engaged by German fighters. On 17 July 1942, during a dogfight with Bf 109s, he became separated from his wingman Konstantin Figichov, and was jumped by a "Rotte" of Bf 109G-2 "Gustavs" flown by the "experte Feldwebel" Hans Dammers and his wingman "Unteroffizier" Kurt Keiser (7./JG 52). Initially Pokryshkin dived to escape, but realizing that the heavier and faster Gustavs would catch him, he performed a chandelle and then a barrel roll. This caused the Germans to overshoot, and then Pokryshkin shot down (and killed) Keiser at short range. Dammers attacked Pokryshkin shortly afterwards, damaging his Yak-1. But once more Pokryshkin performed a barrel roll, forced Dammers to slide forward, and then shot down the German ace.