GOLD COAST, Australia — Taylor Ruck has been surprising people for months. On Thursday she surprised herself.

The 17-year-old phenom from Kelowna, B.C., won the 200-metre freestyle final in a Commonwealth Games and Canadian record time of one minute 54.81 seconds, erasing the mark of 1:55.57 set four years ago by defending champion Emma McKeon of Australia.

“Going into this race I think my expectations were just to try and get third which is what I was going in at (as the third-highest qualifier at 1:57.44),” said Ruck, who won two relay bronze medals in the Rio Olympics. “So anything better than that I was just going to be super happy.”

Ruck had to stave off a hard-charging Ariarne Titmus, a 17-year-old who won the 200, 400 and 800 freestyle at the Australian Commonwealth Games trials five weeks ago, in a heart-pounding final lap.

“An absolutely tremendous performance,” said Swimming Canada high performance director John Atkinson.

Ruck then teamed up with Toronto’s Penny Oleksiak and Kayla Sanchez and Alexia Zevnik of Montreal to earn silver in a 4×100 relay won by Australia in a world-record time of 3:30.05.

Ruck brought the Canadians home with a blistering 51.82-second anchor leg for a time of 3:33.92. The Canadian record is 3:32.89, set by Oleksiak, Ruck and company in a bronze medal performance in Rio.

Canada also picked up another silver in the pool, thanks to Sarah Mehain of Vernon, B.C., placing second in the women’s S7 (para) 50-metre butterfly. Tess Routliffe of Caledon, Ont., was third but did not get a bronze because there were only four competitors.

“It’s been a great day,” said Atkinson.

Ruck was second behind McKeon over the first 100 metres, but led after 150 metres and held off Titmus, who was fourth midway through the race, to touch the wall first.

“Great athletes know how to finish races and she finished it off well,” said Atkinson.

Ruck wasn’t so sure.

“I saw Ariarne coming up and I thought she won. So it was like ’Oh my gosh’ when I looked up at the board. I think I’m still in shock. I don’t think I’ve processed it yet.”

Getting her gold medal from Prince Charles wasn’t much of a help in terms of a reality check. “That was insane,” she said, adding: “He was really nice.”

Titmus was four one-hundredths of a second behind Ruck in the 200 in a personal best time of 1:54.85 while McKeon, the bronze medallist in Rio, was third in 1:56.26.

Ruck also had to knife through a wall of sound at the Optus Aquatic Centre, with the crowd of 10,000 doing its best to power the Aussies on home.

Oleksiak, who won the 100 freestyle in Rio but did not compete in the 200 there, was seventh in 1:59.55.

“I think the relay was amazing and Taylor’s 200 free was crazy,” said the four-time Olympic medallist, whose grandmother died on the eve of the meet. “Overall I think it was a really really good night for Canada and I’m just excited for the rest of the meet.”

Oleksiak finished second in her 100 butterfly semifinal to qualify for Friday’s final.

Ruck, who has verbally committed to attend Stanford University, has been serving notice recently that she is something very special.

She had set the Canadian record of 1:56.85 in the 200 freestyle in March in Atlanta with a sizzling swim in the final TYR Pro Swim Series stop in her final tune-up before the games. Ruck won three other events at the Atlanta meet including the 100 free where she beat world record-holder Sarah Sjostrom.

Ruck, who was born in Kelowna but moved to Scottsdale, Ariz., with her family when she was young, switched things up last year after failing in April to qualify for the world championships. She moved to Toronto in May to train with coach Ben Titley at the High Performance Centre-Ontario.

“Ben refocused her on going to the world junior championships,” said Atkinson.

Ruck responded by winning seven medals — six gold and one silver — at the 2017 FINA World Junior Championships last August in Indianapolis.

At the Swim England National Winter Championships in December, she tied the 200 freestyle Canadian record and trimmed her 100 free and 200 backstroke times, setting a Canadian national age group record (15-17) in the 200.

Ruck came to the games with four times in the top eight in the world (in the 100 and 200 backstroke and 100 and 200 freestyle).

Atkinson calls it a “breakout meet” for Ruck, a six-footer with an equally big smile. Unlike Rio where she competed only in the relays, she has three more individual events here plus relays.

“The work that she’s been doing in a lot of these swim meets over the last year is preparing her to come here, be busy, work on recovery strategies between heats, finals, semifinals,” said Atkinson. “And we want her to be swimming just as fast on Day 6 as she is on Day 1.”

There were five other finals Thursday, with England winning four and Australia one.

Ottawa’s Erika Seltenreich-Hodgson finished 0.28 seconds out of a medal, finishing fourth in the women’s 400 IM final won by England’s Aimee Willmott. Two-time defending champion Hannah Miley of Scotland was second and Australia’s Blair Evans third.

For Seltenreich-Hodgson, the disappointment of missing out on a medal was tempered by the fact she was coming back from a shoulder injury that has limited her preparations. The time of 4:38.51 was her best in four years.

Victoria’s Sarah Darcel led for more than half the race but was pegged back and finished fifth. Mary-Sophie Harvey Trois-Rivieres, Que., was eighth.

Victoria’s Jeremy Bagshaw was fifth in the men’s 400 freestyle won by Australian Mack Horton.

The six-day swimming event wraps up Tuesday.

Four years ago in Glasgow, Canadian swimmers won 11 medals (4-1-6) to finish behind England’s 28 (10-10-8) and Australia’s 57 (19-21-17).

Ryan Cochrane and Audrey Lacroix, who won three of those gold medals in Glasgow, have since retired. Katerine Savard, who won the other gold four years ago, pulled out of these Games due to illness.