His only blip was the early-season race in April 2004, which was taken out by Kelly.
Freshly 21 years old, Kelly was basking the afterglow of a Bathurst win with Greg Murphy in 2003, when he became the youngest driver to win the great race.
Ambrose opened the 2004 season with an Adelaide sweep, with Kelly only good enough for finishes of 12th and sixth.
In Sydney, Kelly showed that his Bathurst win with Murphy was no fluke, becoming the youngest driver to win a championship round.
Eastern Creek became a river after the late downpour
Ambrose looked to continue his dominant Eastern Creek winning run with pole position.
However, a lap 51 off saw Ambrose drop down the field, having already ceded the lead to Kelly. He would finish seventh.
However, the skies darkened and the heavens opened. The Safety Car was deployed, and the race was called 10 laps short of its 77-lap distance.
It was good timing for Kelly, who had Lowndes on his bumper when the race was neutralised.
"This is a great result, not only for me but also my Kmart Racing team-mates who have worked extremely hard all weekend and never gave in, it feels absolutely fantastic,” Kelly said afterwards.
"If this race had been run yesterday, we clearly wouldn't have been in contention, but the conditions changed and our car was incredible in the wet.
"Apart from having a problem changing a wheel during our pit-stop, we had a very good run today and seemed to have no trouble passing other cars, either down the inside or around the outside.
"It was the correct decision to make, the conditions made it impossible and unsafe to continue the race and I was relieved to see the [red] flag come out.
"Had we returned to racing, though, I was confident we had the speed to stay in front until the finish."
Sydney Motorsport Park will host the first of four events, the Bunnings Trade Sydney SuperNight, from October 29.