It was only two years ago that Eugenie Bouchard made her arrival on the big stage at the Australian Open, reaching her first Grand Slam semifinal and talking confidently about how she always expected to be one of the game's stars.

Since then, the young Canadian has had a meteoric rise to the top of the rankings, followed by a dramatic decline and freak head injury — all by the age of 21.

Back in Rod Laver Arena on Wednesday, the Westmount, Que., native showed flashes of the game that took her to the Wimbledon final in 2014 — but also plenty of rust — as she lost in the second round to fourth-seeded Agnieszka Radwanska 6-4, 6-2.

"I felt at times my level was high, but it's just about having that consistency throughout the whole match," a downcast Bouchard said afterward.

Consistency is what's been lacking for the Canadian since midway through her breakout season in 2014. After reaching the semifinals at the Australian Open and French Open and then the Wimbledon final — surging to the top 5 in the rankings — Bouchard began a downward slide that hasn't really stopped.

Her troubles began shortly after losing the title match to Petra Kvitova at the All England Club. She went 9-10 the rest of 2014 and parted ways with longtime coach Nick Saviano.

Then came a tumultuous 2015 season in which she won only three matches from March to August and split with another coach, Sam Sumyk. She seemed to turn a corner by stringing together three wins at the U.S. Open, but slipped in the locker room and slammed her head on the floor, causing a concussion and forcing her to withdraw. She later filed a lawsuit against the U.S. Tennis Association.

Now fully recovered from the fall, Bouchard came to Australia hoping for a fresh start. She made the final at last week's Hobart International.

"I was able to come over here and play three weeks in a row and that's a victory for me no matter what the results are," she said.

Against Radwanska, Bouchard also looked sharp at times, driving powerful groundstrokes down the line the speedy Pole couldn't touch. She broke Radwanska to go up 4-2 in the first set but then made three straight errors in the next game to give the advantage right back.

Bouchard had 25 winners — nearly three times as many as Radwanska — but also 37 unforced errors.

"Against a great player like her, you can't ever back off or give her a chance to breathe," she said. "I have to remember that's how it goes in tennis."

It's now been nearly a year and a half since Bouchard's last top-20 win, but she's no longer expecting to an immediate return to the top. "I've missed out, I feel, so much so I kind of almost want to play catch-up in terms of matches," she said. "No matter what happens, if I lose every match, I'm happy to be doing what I love."

Nestor, Pospisil advance in doubles

Earlier Wednesday, both Toronto's Daniel Nestor and Vasek Pospisil of Vancouver made it through to the second round of men's doubles.

Nestor and partner Radek Stepanek of the Czech Republic needed just 58 minutes to dispatch Tsung-Hua Yang and Cheng-Peng Hsieh of Taiwan 6-1, 7-5 in their match, rattling off five aces and winning 86 per cent of their first-serve points.

Earlier this month, Nestor became the first player in ATP Tour history to record 1,000 doubles victories with a win in the opening round at the Apia International in Sydney.

In their match, ninth-ranked Pospisil and partner Jack Sock of the U.S. defeated Philipp Petzschner of Germany and Alexander Peya of Austria, 1-6, 7-6 (5), 7-6 (5).

In women's doubles, Gaby Dabrowski of Ottawa and Polish partner Alicja Rosolska lost their first-round match in one hour 36 minutes, falling 6-1, 7-6 to Johanna Konta and Heather Watson.

Dabrowski and Rosolska double faulted 11 times and had 31 unforced errors to 19 from Konta and Watson.

No. 13 seed Milos Raonic of Thornhill, Ont., will face unseeded Spaniard Tommy Robredo late Wednesday in second-round play. Raonic won his opener in three sets over Lucas Pouille of France.

Top seeds Serena, Djokovic roll on

There's no doubt Novak Djokovic and Serena Williams feel right at home on Rod Laver Arena, where they've won a combined 11 Australian Open titles.

With five, Djokovic has already won more Australian titles than any other man in the Open era. He beat 19-year-old French wildcard entry Quentin Halys 6-1, 6-2, 7-6 (3) on Wednesday night to reach the third round here for the 10th straight year, moving another step closer to equaling the all-time record of six Australian titles set by Roy Emmerson in the 1960s when it was amateur.

Halys was overawed to start with, losing the first seven points to be down a 1-0 and facing triple break point before he managed to hold serve in a game lasting 10 minutes. He was level for a couple of minutes, before Djokovic went on a roll to win the next seven games. Djokovic lost only one match at a Grand Slam tournament last year — the French Open final. At Melbourne Park, he has lost only one match in the previous five tournaments. He gives even the second-round matches a sense of occasion.

"This court just gives me so many beautiful memories, wonderful time," Djokovic said. "Every time I step on the court it feels special."

Williams has had so much success for such a long time that even in a second-round match she can set a record at the season's first Grand Slam event.

The six-time and defending champion beat No. 90-ranked Hsieh Su-wei 6-1, 6-2, an all-time record 79th main draw match at the Australian Open.

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Defending champion Serena Williams breezed through to the third round at the Australian Open with a straight sets victory over No. 90-ranked Hsieh Su-wei. (Vincent Thian/The Associated Press)

"It all started here — this is where I played my first Grand Slam right on this court and I'm still going, it's such an honour," said Williams, who has a 70-9 win-loss record at Melbourne Park since her debut in 1998. "I love it every time I come here."

Williams' next opponent will be 18-year-old Russian Daria Kasatkina, who beat Croatia's Ana Konjuh 6-4, 6-3, and she faces a potential quarterfinal match against 2015 finalist Maria Sharapova, who reached the third round with a 6-2, 6-1 win over Aliaksandra Sasnovich.

In the biggest upset of the day, two-time Wimbledon champion and sixth-seeded Petra Kvitova was beaten 6-4, 6-4 by Russian-born Australian Daria Gavrilova.

No. 10 Carla Suarez Navarro, No. 12 Belinda Bencic and No. 13 Roberta Vinci advanced along with 92nd-ranked Kateryna Bondarenko, who earned one of her biggest wins since returning from retirement in 2014 with a straight sets win over two-time major winner and No. 23-seeded Svetlana Kuznetsova.

Federer into 3rd round for 17th straight year

For a long time, Rod Laver Arena just about belonged to Roger Federer. The four-time champion may not have won a title here since 2010, but he has extended his streak of reaching the third round at the Australian Open to 17 consecutive years.

Federer, playing his 65th consecutive major, advanced 6-3, 7-5, 6-1 over Alexandr Dolgopolov. It was his 299th match win at a major.

He lost in the third round in his first two trips to Melbourne Park in 2000 and '01 and again last year — in between he won the title four times and lost one final during a run of reaching the semifinals or better in 11 straight years.

"It's the least I expect to be in the third round of a Slam, obviously, so I'm pumped up, playing well, feeling good.

"But there's always a danger, you know. Like last year the third round was the end for me, so I hope to go further this time."

Federer will next play Grigor Dimitrov, who has a style that has been compared with Federer's, after the No. 27-seeded player beat Marco Trungelliti 6-3, 4-6, 6-2, 7-5.

Jo-Wilfried Tsonga went to the aid of a ball girl in his match, gently helping her off the court in the third set when she became ill before finishing off a 7-5, 6-1, 6-4 win over Omar Jasika.

Other seeded men's players joining in the third round included No. 6 Tomas Berdych, No. 7 Kei Nishikori, 2014 U.S. Open champion Marin Cilic, No. 14 Gilles Simon, No. 15 David Goffin, No. 19 Dominic Thiem and No. 24 Roberto Bautista Agut.

With files from CBC News and The Canadian Press