Everyone loves a good rivalry, and Sophie Pascoe and Summer Ashley Mortimer have got their version of Phelps v Lochte or Bolt v Blake fizzing along in the pool at the London Paralympics.

The Kiwi and the Canadian will clash for the last time at the Games tomorrow morning (NZ time), in the S10 women's 100m freestyle, and the scoreline reads 2-1 Mortimer after she edged Pascoe in the 100m backstroke yesterday. Mortimer also pipped Pascoe to gold in the 50m freestyle after the Christchurch star had taken an early lead in their head-to-head battle by winning the 200m individual medley on the opening day.

The three events in which the two 19-year-olds have competed against each other have seen world records smashed. Pascoe's fourth medal, a gold, came in the 100m butterfly, which did not feature Mortimer.

"She had the drive to get there," Pascoe said of her rival after the backstroke final yesterday.

"I did want it but unfortunately I couldn't sit on her tail. I've given it everything and that's all I can ask of myself. I left everything in the pool and I'm happy with my time."

Pascoe set a Paralympic record and personal best of 1min 7.77sec in the morning heats, qualifying fastest, but Mortimer responded emphatically with a world record 1:5.9 to pip Pascoe in the final.

The former Lincoln High School student still notched a personal best of 1:6.69, an Oceania record and more than 1sec quicker than her Games record-setting time in the morning but Mortimer, who hails from Hamilton, Ontario, had a big finish after trailing Pascoe at the turn.

"Unfortunately she pipped me at the post again but I had nothing left in me," Pascoe said.

"I'm all cramped up . . . so I know I've given it my all.

"It's a new personal best for me and that's all I can do."

Mortimer was a top swimmer and trampolinist before she broke most of the bones in her feet in a trampolining accident in 2008, soon after missing out on selection to the Canadian team for the Beijing Olympics. She required plates and screws in her feet and her condition is degenerative.

Pascoe is a below-the-knee amputee after a lawnmower accident when she was 2, and both qualify for the S10 category, which is defined as minimal physical impairment. Pascoe's medal tally from four events now sits at two golds and two silvers. From Beijing, she returned home with three golds and a silver.

There is every chance she will eclipse that tally with the 100m freestyle tomorrow and the S9 women's 100m breaststroke on Sunday (NZ time) still to come.

New Zealand had 12 medals - four of each colour - with four competition days remaining, slotting in at 19th on the medal table.

- © Fairfax NZ News