- Roger Federer hopes to win "about five" tournaments in 2014 and play in "great" finals
- The Swiss ends 2013 at No. 6, his lowest year-end ranking since 2002
- Serena Williams is one major short of tying Martina Navratilova and Chris Evert
- Andy Murray returns to the pro circuit in 2014 after undergoing back surgery in September
Roger Federer took time out from his off-season training regimen to answer questions on Twitter from his legions of fans.
Among the things they learned earlier this month was that Federer's favorite fruits were strawberry, apple and mango and that he has visited 55 countries.
When asked what he planned to get wife Mirka for Christmas, the funnier side of the 17-time grand slam champion emerged: A "hashtag," he replied.
He added that he was "working overtime" to win the Australian Open in January -- which leads us to the first of five burning questions looking ahead to the 2014 tennis season.
Can Roger Federer win another grand slam?
The numbers, so often in favor of history maker Federer, were less kind to the Swiss in 2013.
He failed to reach a grand slam final for the first time since 2002, his grand slam quarterfinal streak ended at 36 and his year-end ranking of No. 6 was his lowest in 11 years.
Federer only won one tournament, on grass in Halle, Germany -- though he was bounced from Wimbledon a few weeks later in the second round after claiming the title at the All England Club a record seven times.
Longtime coach Paul Annacone was axed months later.
His back problems returned, with Federer saying it was a mistake to keep playing at the BNP Paribas Open in March when the back flared up.
It was indeed a slump -- well, for Federer.
But Federer says he is now fit, which helped the 32-year-old finish the season on a high.
"My self-confidence has also returned," he told the website of one of his sponsors, Credit Suisse, in late November. "By the end, everyone around me was talking positively again. The mood was much better than in the summer.
"That boosts my morale for the coming year, and it's a big relief. The fun has definitely returned."
Federer said he would like to win "about" five tournaments in 2014 and play in "great finals."
The majors are what matter to Federer most, and if he was to claim the Australian Open he would become the second oldest man -- behind Andre Agassi -- to bag a singles grand slam in the last 40 years.
Federer probably needs to beat two of Rafael Nadal, Novak Djokovic and Andy Murray to collect an 18th major but his recent record against the trio is underwhelming.
He has lost four straight to Nadal, three straight to Djokovic and fell to Murray in an absorbing Australian Open semifinal last January.
No matter what happens to Federer in 2014, though, he'll still be a major talking point.
Can anyone stop Rafael Nadal at the French Open?
Statistically, Nadal became the best player ever at the French Open when he won an unprecedented eighth title on the red clay at Roland Garros.
Only once has he failed to win in Paris in the spring, when Robin Soderling, Nadal's wonky knees and the then split of the Mallorcan's parents made for a combination too powerful to overcome in 2009.
Since then he has captured four in succession.
But Nadal came within an inch of likely losing at the French Open this year to Djokovic. The Serb led by a break 4-3 in the fifth set of their semifinal when he touched the net before a point ended at deuce. It was an easy put away that Nadal had no chance of reaching.
Djokovic lost the point, Nadal broke back and he won 9-7 in the fifth.
Only two months prior, Djokovic snapped Nadal's 46-match winning streak, dating back to 2005, at the clay-court Monte Carlo Masters.
If anyone is to get the better of Nadal at the French Open next year -- assuming he is healthy -- Djokovic, who has appointed Boris Becker as the head of his coaching team, is the lone serious candidate.
Who can derail Serena Williams?
Serena Williams compiled a 78-4 record in 2013 for the best winning percentage on the women's tour since 1990 and she took home nearly $12.4 million in prize money -- the most ever for a female tennis player in a season.
Williams was stunned by Sabine Lisicki at Wimbledon in one of those four losses but weeks earlier lifted the French Open trophy for the first time since 2002.
When she triumphed at the U.S. Open in September, the American climbed to 17 majors to approach Chris Evert -- once her critic -- and Martina Navratilova.
Unlike her fellow 32-year-old Federer, Williams doesn't have as many roadblocks in front of her so she could keep on collecting grand slam titles in bunches.
World No. 2 Victoria Azarenka has yet to win a grand slam outside Australia and Maria Sharapova is returning from another serious shoulder injury. They're Williams' two main rivals.
Williams' first order of business is to end Azarenka's two-tournament reign in Melbourne after injuries hampered her Down Under in 2012 and this year.
How will Andy Murray recover from his back injury?
Murray missed the last two months of the season following back surgery and all eyes are on the Scot to see how he'll rebound in 2014. As the likes of Federer, Agassi and Murray's coach, Ivan Lendl, can attest, back problems are difficult to shake.
He is due to return to action at an exhibition tournament in Abu Dhabi on Boxing Day against Jo-Wilfried Tsonga and might also face Djokovic and Nadal.
"It's exactly the test I need to see where my game is at," Murray was quoted as saying by ESPN UK online.
Thankfully for Murray he was able to end Britain's 77-year wait for a men's singles champion at Wimbledon -- before the back forced him off tour -- when he toppled Djokovic in July.
Prior to Nadal re-emerging on the circuit in February, Djokovic and Murray contested two straight grand slam finals.
Murray wants to make more history, said mom Judy.
"Andy's goal is to win more grand slams and try to achieve that end-of-year world No. 1 ranking," she was quoted as saying by the Scotsman newspaper this week.
Can anyone new win a major?
With the men's Big Four around, unearthing a new grand slam champion in 2014 figures to be difficult.
Since the spring of 2005, only one man not named Federer, Nadal, Djokovic or Murray has won a grand slam -- Juan Martin del Potro at the 2009 U.S. Open.
Recent years, however, tell us it could happen on the women's tour. For four straight seasons a debutante has come through at a major, Marion Bartoli being the most recent at Wimbledon.
Bartoli was the first to admit she benefited from a nice draw, with Williams, Sharapova and Azarenka all exiting before the quarterfinals.