Ambrose, who has won the last two Cup races at Watkins Glen International -- the Australian's only victories in the series -- turned a lap of 128.241 mph in his Ford on Saturday to capture the first starting spot.
"I've never had a pole position here, so I dug deep and put down a solid lap and it was enough," Ambrose, 36, told reporters at the track. "It's a very special moment for me."
Stewart suffered a broken right leg in a sprint-car race Monday in Iowa. Stewart, a three-time Cup champion, is out indefinitely after two surgeries to repair the leg.
Among other notable drivers,