Here's a look at what has changed since the end of the season and the beginning of the Australian Open:
1. The Australian Open courts may play faster than previous years. Players reported quicker conditions than expected during last week's event in Brisbane, where the courts are prepared the same way as at the Australian Open. But final word will have to wait until the field arrives en masse to begin practicing on site. Tournament organizers deny that anything is different this year, and factors like weather, amount of use and playing conditions can all affect court speed. Either way, rumors of the change have already reached Rafael Nadal. "I thought [Australian Open tournament director] Craig Tiley was a friend of mine," joked the Spaniard, who prefers slower courts.
2. There's no question that Margaret Court Arena, the fourth-largest court at the Australian Open, will feel different than before. The stadium has been refurbished with a roof and extra seating.
3.Roger Federer has a new coach on board as he attempts to put last season's struggles behind him. Childhood idol Stefan Edberg will start a 10-week stretch with the 17-time Grand Slam champ at the Australian Open.
4. Federer has also gone to a 98-inch frame, in lieu of the 90-inch model he played with for more than 10 years. The new stick is not the same as the one Federer experimented with for a few weeks last season, but another version he spent time practicing with in the offseason. "The racket suits me very well," he said.
5. Another new development: Federer and his wife, Mirka, are expecting again, with the baby due to arrive sometime this year. The couple already has twin girls, Charlene and Myla Rose, who were born 3½ years ago.
6. Novak Djokovic has also taken on a legend as coach, with Boris Becker joining the Serb since the beginning of this season. Djokovic says he wanted an experienced hand to help him prepare mentally for big matches like Grand Slam finals.
7. Caroline Wozniacki and Rory McIlroy are engaged. After more than two years of dating, golf champion McIlroy popped the question during New Year's celebrations in Sydney, where Wozniacki is playing this week.
8. Ryan Sweeting, meanwhile, got married on New Year's Eve to actress Kaley Cuoco. The two began dating last year and became engaged a few months ago.
9. Bob Bryan and his wife, Michelle, had a boy just before Christmas. It is the couple's second child. Daughter Michaela, born just under two years ago, has become something of a social media celebrity (@MicaelaBryan), and Bobby Jr. already has been given a Twitter account (@BryanBrosJr).
10. Janko Tipsarevic is also set to become a father. He and his wife, Biljana, are expecting their first child later this year.
11. Tipsarevic will not be able to play the Australian Open, however, withdrawing with a foot injury that also affected him last year. Jurgen Melzer (shoulder surgery), Viktor Troicki (suspension), Brian Baker (knee) and Maria Kirilenko have also withdrawn.
12. Those are just a few of the injuries that have marked the new season. More than two dozen players have withdrawn or retired from tournaments during the first week, including Sloane Stephens (wrist), John Isner (ankle), Laura Robson (wrist), Fabio Fognini (leg), Jamie Hampton (hip), Vasek Pospisil (back) and Flavia Pennetta (wrist).
13. Andy Murray has returned from back surgery. He lost in the Doha quarterfinals in his first event since the US Open. Murray says he has "no idea" how he might do at the Australian Open, where he reached the final last year.
14. Rafael Nadal tried a knee treatment during the offseason that was a "little bit different," and says his knee is now less painful during regular activities.
15. Serena Williams is focusing on trying to be ''more relaxed'' during matches this season. "If I play relaxed, I just feel a lot better. I'm really going to try to incorporate that mainly in the Grand Slams," Williams said early on at Brisbane.
16. But it only goes so far: "One of my goals is to stay relaxed, but I don't want to fall into the trap of not having the intensity," she added after playing a tough match in the final.
17. After suffering ankle injuries during the past two years in Australia, Williams is also wearing shoes with ankle supports built in. They consist of a purple edging visible around the sock line.
18.Venus Williams has begun the new season well, reaching the final in Auckland before losing in three sets to Ana Ivanovic. She says her inconsistency stems from a lack of matches and plans to keep playing aggressively, saying, "There are only so many you are going to miss."
19. Maria Sharapova has begun working with a new coach, Sven Groenefeld, who occasionally coached Wozniacki while he was with adidas.
20. Wozniacki is working with Thomas Hogstedt, who previously coached Sharapova.
21. There may be two new all-American couples on the tour. Ryan Harrison and Lauren McHale, the college tennis-playing sister of Christina, tweeted a picture together during Thanksgiving. Sloane Stephens and Jack Sock also sent out a photo of themselves during Christmas.
22. Marin Cilic says his coach, former Wimbledon champ Goran Ivanisevic, has helped his serving by simplifying the process and telling him just to "throw the ball up and hit it."
23. Grigor Dimitrov, selected as the shot-maker of the year around these parts, has new coach Roger Rasheed telling him "no more shenanigans." Dimitrov, 22, has been ordered to play more solid tennis and wear more manly colors as he attempts to break into the top 20 this year, according to the Melbourne Age.
24. Juan Martin del Potro and Dimitrov have joined new management company Team8, started by Federer and his agent, Tony Godsick.
25. Kei Nishikori hopes new coach Michael Chang can propel him into the top 10.
26. New ATP CEO Chris Kermode has started in his latest role, saying he wants to continue "the growth we've seen in the sport in recent years" and try to "build decisions through consensus."
27. Former pro Amer Delic, who represented the U.S. and later his birthplace of Bosnia during his playing days, has been named the Davis Cup captain for Bosnia and Herzegovina.
28. Richard Gasquet has replaced former coach Ricardo Piatti with former French Open champ Sergi Bruguera. Piatti left the Frenchman unexpectedly toward the end of last season and has since joined Milos Raonic's camp. Gasquet also has a new clothing sponsor, Le Coq Sportif.
29. After struggling physically last year, Victoria Azarenka has a new fitness trainer, Christa Pryor, and not one new physio but two -- Stephanie Turpin and Fabrice Gautier. Two of the three are women, prompting Azarenka to joke, "I wanted more women on my team because I'm always surrounded by men."
30. Ross Hutchins, who missed last season after being diagnosed with Hodgkin's lymphoma, is back on tour. The British doubles specialist played Brisbane and Auckland with his regular partner, Colin Fleming.
31. Leizel Huber has decided to shelve retirement plans and play for another year.
32. On top of all the other new things he's trying, Federer came up with a new trick last week as well.
33. Lleyton Hewitt is looking renewed after defeating Federer to win Brisbane. The former No. 1 had struggled with injuries during the past few years but says he is now pain-free and was finally able to train properly during the offseason.
34.Sam Querrey, speaking to USA Today, says he struggled with motivation after splitting up with his fiancée last year. ''Mentally I don't think I was all there,'' he said.
35. Sloane Stephens is being coached by Paul Annacone, who stopped working with Federer last year.
36. Alexandr Dolgopolov also has a new coach, Fabrice Santoro. Both have unorthodox playing styles, resulting in a pairing that got the approval of Andy Murray. "Fabrice Santoro doing some work with dolgopolov … has to be the best coach/player fit out there! #unpredictable," he tweeted.
37. Speaking of which, Murray became the latest player to hold a Twitter Q&A, which has gained popularity after the success of Federer's "AskRF" session. Among the topics addressed by Murray was Feliciano Lopez, the Spaniard who is publicly admired by Murray's mom, Judy. Admitted Murray in a tweet, "He is a beautiful man ... maybe too beautiful ... but he's definitely beautiful."
38. The once long-haired Lopez is, however, sporting a crew cut as this season begins.
39. Tommy Haas is also playing with new rackets as he tries to re-enter the top 10 at the age of 35.
40. Haas is no longer that far from the norm. Three of the six finals played last week were won by players over 30 -- Serena Williams, Lleyton Hewitt and Li Na. Two other finalists, Roger Federer and Venus Williams, also fall into that group. Nadal (27), Stanislas Wawrinka (28) and Ivanovic (26) were the other champs.