Open this photo in gallery Bianca Andreescu of Canada celebrates her victory against Venus Williams at the ASB Classic tennis tournament in Auckland, New Zealand, on Jan. 4, 2019. DAVID ROWLAND/AFP/Getty Images

Canadian tennis player Bianca Andreescu made two key decisions last year that have helped her kick off the 2019 campaign in style.

After recovering from a back injury last summer, she decided to focus on the lower-level Challenger series and quickly returned to form. Andreescu also moved her off-season training location from Boca Raton to the IMG Academy in Bradenton, Fla., which allowed her to practise against tougher opponents.

Those calls helped Andreescu start this season feeling strong and assured. The players she has eliminated at the ASB Classic – including former world No. 1s Caroline Wozniacki and Venus Williams – can attest to that.

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“She showed up in Auckland full of confidence and playing really, really well,” said Canadian women’s head coach Sylvain Bruneau. “To be honest, I knew. We’ve been talking and texting. I knew that she was going to get into the main draw and play the top players. I believe in her game a lot.

“It was a matter of her believing that she could just go out there, play her game, lay it out on the court and just believe.”

A day after stunning Wozniacki in straight sets, Andreescu pulled off another big upset Friday by dispatching Williams – a seven-time Grand Slam champion – 6-7 (1), 6-1, 6-3 in quarter-final play.

“I believe that anything is possible and tonight I think I did the impossible,” Andreescu said in an on-court interview after the match. “I don’t even know what to say. It’s just such an amazing feeling.”

Not bad for a teenaged qualifier who started the week ranked No. 152 in the world.

“She’s only 18 and she’s got really, really good potential,” Bruneau said Friday from Melbourne. “From an athletic perspective and also from a competitive standpoint mentally, [she’s] a great athlete. It’s all very exciting. There’s a lot more tennis to [play] and a lot more improvement, [we’ll] keep working.

“For sure that first tournament of 2019 is very positive and reinforces the stuff that we’ve been doing.”

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After losing the first set and dropping the opening game of the second set, Andreescu won 11 straight games against the sixth-seeded Williams.

“I was like, ‘What is going on? I just broke her five times in a row,“’ Andreescu said. “She’s one of the best servers in the game. Today she didn’t serve as well as other matches I’ve seen her play. But I took control of that. It was honestly a gift, maybe like a late Christmas present.”

After winning the first five games in the decisive third set, Andreescu let Williams back in the match.

“I got really tight at 5-0,” she said. “I’m like, ‘I’m one game away from winning this,’ but then she started raising her level and I kind of stepped back. At 5-3, I’m like, ‘OK screw this. I’m just going to go for everything,’ and that’s what I did and it worked.

“Maybe I should just do that every point.”

The 37-year-old Williams, who turned pro six years before Andreescu was born, is ranked 39th in the world. Wozniacki, meanwhile, is the world No. 3 and the reigning Australian Open champion.

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“It feels like a double dream,” Andreescu said.

Next up for the Canadian is a semi-final matchup against third seed and 28th-ranked Hsieh Su-wei of Chinese Taipei. Unseeded Viktoria Kuzmova of Slovakia faces No. 2 seed Julia Goerges in the other semi-final after the German downed Canadian Eugenie Bouchard 3-6, 6-3, 7-6 (6).

Bouchard, from Westmount, Que., did post a doubles semi-final win Friday with American Sofia Kenin. They beat the fourth-seeded duo of China’s Xinyun Han and Croatia’s Darija Jurak 6-7 (5), 6-4, 10-8.

The hard-court tournament is a warmup for the Australian Open. Andreescu will hope to land one of 16 qualifier spots in the 128-player main draw at the first Grand Slam of the season because her ranking is not high enough for direct entry.

After taking time off to rest her back, Andreescu won a Challenger event last October at Florence, S.C. She followed that up with back-to-back semifinal appearances in Saguenay, Que., and Toronto before closing the season by winning a title in Norman, Okla.

Those performances gave her confidence ahead of her off-season practice sessions in Bradenton.

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“She played a lot of sets, a lot of matches there and she kept winning,” Bruneau said. “She kept doing well. She played a bunch of girls in the top 100, top 150. We did some good work. She basically didn’t lose a set in her two weeks there.”

Once in Auckland, Andreescu recorded three straight qualification victories before topping 59th-ranked Timea Babos of Hungary in the first round.

The Canadian has remained consistent during her impressive run at the US$250,000 event. Andreescu, who has battled cough and cold symptoms this week, has used her diverse skill set to flummox her opponents.

“Bianca has this dimension where she’s able to do more,” Bruneau said. “She’s able to really change it up with quality. Hit with spin, topspin, slice, she’s got a great drop shot. She’s able to hit a very heavy ball.”

Those thoughts were echoed by Andreescu’s frequent doubles partner Carson Branstine.

“She can do any shot you can ask of her,” Branstine said from Orange County, Calif. “I really think that it might throw a lot of girls off because they’re not used to a girl like Bianca playing. There’s a lot of women that kind of just play one way, where Bianca can play any game style that she needs in order to win matches.

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“I think that’s going to really benefit her in the future because there aren’t very many people who can actually do it like she does.”

Andreescu will top her career-high ranking of No. 143 (set Aug. 14, 2017) when the new list is released next week, WTA Tour statistics and information director Kevin Fischer said in an email.

It’s too early for specifics since other results may factor in, but she’s projected to move to No. 114 by reaching the semifinal. A win on Saturday could bump her up to No. 107 and a victory in Sunday’s final could launch her as high as No. 89.

Andreescu’s surprise performance has moved her to the front of sports pages across the country and generated plenty of buzz on social media. Bruneau said Andreescu is prepared for the heightened attention.

“You just need to be really grounded,” he said. “We know she’s ranked around 150. She’s going to go up in the ranking with this but we’re still very far from where I think she could be.

“So it’s all about keep working, progressing, stay in the moment and do the right thing.”