Korpisalo makes 35 saves for Columbus.
Early lead vanishes for Columbus.
Okposo has goal, assist for Sabres, who snap 5-game losing streak.
Bobrovsky charts 42 saves.
Columbus back home Sunday against Florida.
Ottawa scores twice in third period to stop 4-game slide.
Pittsburgh, Columbus have gone to OT in 4 of last 5 regular season meetings.
Bobrovsky stops 30 shots for Columbus in 20th win.