The defenceman, who hadn't netted a goal in 10 games, took the puck at the right point - after Steve Rucchin won an offensive zone faceoff - skated all the way down to the right post and flicked a short backhander that pinballed off goalie Henrik Lundqvist and found its way between his pads.
That was enough to give the Southeast Division-leading Thrashers their third win in four games and send them into the all-star break well on the way to their first playoff berth in seven NHL seasons.
New York will limp into the hiatus, having lost four of five and 11 of 16. The Rangers, who failed to get a single power-play chance in a 1-0 loss at New Jersey on Tuesday, had six opportunities Saturday but couldn't convert. The Rangers have killed 16 consecutive opposition power plays but haven't connected on their past 16.
Kari Lehtonen was a big reason why. The third-year goalie made 29 saves and won for the third time in four starts after dropping four straight.
Ilya Kovalchuk gave the Thrashers a 1-0 lead in the first period before Jaromir Jagr tied it just more than three minutes later. Marian Hossa, who had a hat trick in Atlanta's loss to Montreal on Tuesday, sealed it with an empty-netter with 23.2 seconds left - his NHL-leading 30th goal this season.
Hossa was stopped on a penalty shot in the second period after Rangers defenceman Fedor Tyutin threw his stick at the puck.
Henrik Lundqvist was sharp in New York's net, too, stopping 29 shots. But the Rangers equalled last season's total by losing for the 10th time at home (10-10-3).