Roger Federer, Maria Sharapova and the quest for gold

The stars are back as the countdown to the Australian Open begins.

We know the big storylines to follow: Will Serena Williams, if healthy, rebound from her disappointing end to 2015 and make another run at a season Slam? Perhaps a Golden Slam, à la Steffi Graf in 1988?

And just how far up the tennis pantheon will Novak Djokovic end up at season's end? If he sweeps the majors, he would have 14 and be tied with Pete Sampras for second all time.

But with all due respect to the world No. 1s, we'll focus on the other players hoping to generate positive headlines this year.

Our top questions as the tennis circuit resumes:

Will Roger Federer win a first Olympic singles gold medal?

The Rio Games is Federer's last chance to win the only big prize still missing from his collection of tennis baubles. Although Federer already has an Olympic gold medal from doubles, after partnering with Stan Wawrinka to success in Beijing eight years ago, he has underperformed in the singles tournament. His best finish was in 2012, when he didn't win a set in the final against Andy Murray.

A glance at Federer's schedule for the year -- he is taking a two-month break between Indian Wells and Roland Garros to save himself for a busy summer -- confirms how badly the Swiss wants to stand on top of the podium in Brazil. Twice already Federer has carried Switzerland's flag during the opening ceremonies.

The pressure is on as he goes for the gold.

Will Eugenie Bouchard return to the tennis elite?

Bouchard, a Grand Slam finalist just a year and a half ago, could drop out of the top 50 after the Australian Open, with the Canadian defending a large number of points after making last year's quarterfinals. She showed flashes of her brilliant game at the US Open before an unfortunate slip-and-fall accident forced her to withdraw from the tournament.

It's difficult to imagine that Bouchard's 2016 could be worse than last season, when she won just 12 matches. The biggest buzz she generated was the pending lawsuit she has against the United States Tennis Association related to the fall.

If Bouchard can get her act together, the WTA will be in a much better place.

How will his Davis Cup victory and pending fatherhood change Murray?

If Djokovic's path is any indication, Murray's future promises to be a superb. His wife, Kim, is due to give birth to their first child in February. But timing could be key. Murray has openly said he would pull out of the Aussie for the birth.

After becoming a father in late 2014, Djokovic had his finest season at the Grand Slams in 2015, with 27 victories in 28 matches.

And just as Djokovic did in 2010 before winning three majors the next season, Murray is coming off an inspiring Davis Cup victory. More than anything in 2015, this is what Murray wanted.

Will Garbine Muguruza score her first Grand Slam title?

The runner-up to Serena Williams at last summer's Wimbledon, the Spaniard finished the season at No. 3 in the rankings and appears to have the game and the mind to win one of the sport's biggest prizes. Perhaps it will come on grass, a surface she once thought didn't suit her game.

What impact will Venus Williams have at the highest level this year?

A few days before this summer's Wimbledon championships, Williams will turn 36. But, just like her sister, Venus' drive and lust for competition has survived into her mid-30s. While Venus isn't now the force that her sister still is, she is putting together results that would be the envy of rivals half her age.

Venus' run at last year's Australian Open was her first Grand Slam quarterfinal in five years. And after reaching the quarterfinals at the US Open, she finished the year at No. 7, her highest placing since 2010.

Make no mistake: Venus is still relevant.

Will Rafael Nadal become the first man in history to win 10 singles titles at the same Grand Slam?

Only twice has Nadal experienced defeat at Roland Garros, against Robin Soderling in the fourth round in 2009 and against Djokovic in last year's quarterfinals.

Last season, Nadal failed to win a major for the first time in a decade. After nine previous triumphs on the Parisian dust, one more would tip him over into double figures. But Nadal is unlikely to have an easy time in Paris this spring -- not with Djokovic so determined to win a first French Open title and accomplish a career Grand Slam.

Will Maria Sharapova win the Olympics?

Like Federer, Sharapova has won everything of note in this sport except the prestigious Olympics. One of the most lopsided defeats of her career was when Serena crushed her in the final of the London Games. Sharapova won only a single game that day.

But first things first: Sharapova has to sustain health. And she's off to a rough start. On Tuesday, she withdrew from the Brisbane International without playing a match because of a sore left forearm, which she had injured a few days earlier in practice. Last season, she played only one event between Wimbledon and the WTA Finals because of a right leg injury.

Will Wawrinka produce another performance as brilliant as the match he played in last year's French Open final?

It's hard to imagine how Wawrinka could play better than he did against Djokovic in Paris last June, a day on which things were going so perfectly that the Swiss managed to strike a ridiculous winner around the net post.

If Wawrinka can touch those heights again -- or even come close -- there is a decent chance that he will add to his two Grand Slams. But whether he can win the French Open in a pleasing pair of shorts -- that's another topic entirely.