Emily Seebohm has set a new Commonwealth and national record in the 200m backstroke at Australia’s short course swimming championships in Sydney.

Seebohm’s sizzling 1:59.49s eclipsed the previous mark of 2:00.13s she set exactly one year ago, but fell just short of the world record 1:59.23s.

Despite clocking three seconds over the magical two-minute mark in her heat, the 23-year-old left her rivals for dead in Thursday night’s final.

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“I didn’t expect the world record, but I said to Mitch (Larkin) this afternoon that I wanted to go under two minutes and I’d be really happy with that,” she said.

The result justified her decision to pull out of the 100m freestyle earlier in the night, despite clocking the fourth fastest time in the heats.

“After my swim this morning, I said I probably wouldn’t go too much quicker anyway,” she said.

“How much would I sacrifice for my backstroke? I’d rather go under two minutes and do a good short course 100 freestyle.”

In a positive sign for the Dolphins ahead of next year’s Olympic Games in Rio, Mitch Larkin also broke the Australian record in the 50m backstroke final with a time of 22.91, while Cameron McEvoy set a new personal best 46.31 seconds in the 100m freestyle final.

Cate Campbell reclaimed her crown in the 100m freestyle, edging out Emma McKeon and sister Bronte, who had held off her elder sibling in August’s World Championships in Russia.

Cate’s time of 51.38 seconds was seven hundredths of a second short of her personal best.

Jessica Ashwood took out the 800m title by shedding exactly three seconds off her PB, just one day after breaking the national and Australian all-comers record in the 1500m.

Ashwood’s 8:16.77 was the best by an Australian in 2015.

One of the most-inspiring stories of the night went to 22-year-old Olympic hopeful Ellen Fullerton, who equalled her Australian record of 4:28.72 in the 400m individual medley, which she set six years ago.