Wimbledon plot lines: What to watch

Roger Federer is once again the favourite at Wimbledon. Photo / AP

As tennis turns to Wimbledon, there's been a bit of a throwback feel to this Grand Slam season so far.

At the year's first major tournament, the Australian Open in January, Roger Federer beat Rafael Nadal for the men's title, and Serena Williams defeated her sister, Venus, for the women's title.

Matchups from a decade ago or more, right?

Then, at the French Open in May and June, Nadal reached a second consecutive major final for the first time since 2014, and won one for the first time since that year.

And now, when play begins at the All England Club, so many of the key story lines will involve those same four players: Federer and Nadal because of their recent resurgence; Serena Williams because of her absence (she's expecting a baby in September); Venus Williams because she is one of only two past champions in the women's draw.

Here is what to watch on the grass courts of the year's third Grand Slam tournament, which starts Monday:

FEDERER THE FAVOURITE

Wasn't all that long ago that folks were figuring Federer's best days were long behind him. He hadn't won a Grand Slam title since 2012, and as he entered his mid-30s, he was missing Grand Slam tournaments for the first time in more than 15 years because of injury. And now? He extended his record with an 18th major championship in Australia, opened the year 19-1, took some time off and then won a grass title at Halle, Germany. With defending champion Andy Murray off-form this season, Federer is a popular pick to win Wimbledon for what would be a record eighth time.

NADAL GOES FROM CLAY TO GRASS

There was a time that Nadal excelled on any surface, winning Wimbledon twice and reaching the final on three other occasions while marching his way toward 10 French Open titles and completing a career Grand Slam, too. But then his knees became a real problem on grass and he not only started losing early at the All England Club, he started losing to players ranked 100th or worse. "When Rafael is good with his knees," said Nadal's uncle and coach, Toni, "he can play well on the grass."

WHO'S MISSING

Not only is seven-time Wimbledon champion Serena Williams absent, but so is 2004 champ Maria Sharapova, who was forced to sit out last year's tournament during a 15-month doping ban. She would have needed to qualify this time around but is now sidelined by a left thigh injury. Their absences lend the same sort of wide-open feel to the women's draw that the French Open had.

KVITOVA, VENUS, AZARENKA

So the two past winners in the field are Venus Williams, a five-time champion, and Petra Kvitova, a two-time champ. Kvitova will get plenty of attention because of what she went through in late December: An intruder attacked her with a knife at her home in the Czech Republic. Kvitova wound up with cuts to her left hand - the one she uses to swing a racket - and needed surgery. Wimbledon will be the third tournament of her comeback; she won the second last week on grass. Another two-time major champion to keep an eye on: former No. 1 Victoria Azarenka. This will be her first Grand Slam tournament in more than a year; she returned to the tour in June after giving birth to a son.

WHICH DJOKOVIC WILL BE THERE?

Novak Djokovic has won three Wimbledon titles and normally would be considered a real likely candidate for a fourth, but he has not played up to his usual standards over the past year. He went from winning four consecutive Grand Slam titles, something no man had done in nearly a half-century, to failing to defend any of those championships; he lost in the third round at Wimbledon in 2016. He tried to look on the bright side recently, saying: "It is liberating a bit. I was very fortunate and privileged to have so much success in the last eight, nine years, and kind of entered most of the tournaments as one of the biggest favorites. So for a change, it's good to not be one of the top favorites. It releases a bit of the pressure."

OSTAPENKO'S FOLLOW-UP

After coming out of nowhere to win the French Open, what will Jelena Ostapenko do for an encore? She arrived in Paris unseeded, ranked only 47th and without a title of any sort on tour, then used a fearless brand of high-risk tennis to win the championship. Now there are new expectations, and no opponent will overlook her, but consider this: Grass is her favorite surface; she was the junior champion at Wimbledon in 2014.