Remember this? Serena Williams, yelling and cursing and shaking a racket at a line judge.
Or this? Roger Federer, losing a Grand Slam final to someone other than Rafael Nadal.
Or this? Maria Sharapova, exiting in the third round against American teenager Melanie Oudin.
Or this? Kim Clijsters, about a month into her second career, celebrating a U.S Open title while her 18-month-old daughter frolicked around the court.
The most unforgettable scenes from the last major championship of 2009 provide hints at what to watch for in tennis in 2010.
Williams' two years of Grand Slam probation for her outburst in New York start at next week's Australian Open, and her on-court demeanor is sure to be monitored closely by fans and officials alike. If she commits another ``major offense,'' she will be banned from a Grand Slam tournament - although no one expects that to happen.
``It was so divergent from the Serena we all know,'' WTA chairman and CEO Stacey Allaster said. ``She has admitted to acting wrongly. She herself said she's not proud of what happened in that moment and apologized on several occasions. She's very determined, and I have no doubt that she's learned from the incident.''
Also worth keeping tabs on, of course, is how well Williams plays, whether she will add to her 11 major singles championships - and how she fares when she eventually faces longtime nemesis and former No. 1 Justine Henin, who is back on tour after about 1 1/2 years in retirement.
``My goal is to have a better year than '09 and to stay healthy,'' Williams said, ``and I think if I can do that, I'll be fine.''
Among the other plot lines and players for fans to track:
-Will doping and gambling be topics of discussion all year?
The Nikolay Davydenko case is in the sport's rearview mirror, but that doesn't mean tennis officials aren't worried about people trying to influence the outcome of matches.
Just last week, former top-100 player Ekaterina Bychkova of Russia was fined $5,000 and barred from playing for 30 days - not because there was any evidence she provided any inside information or took a bribe, but because she failed to report that she was approached by someone who wanted her to.
As for doping, the ``whereabouts rule'' - which requires players to make their whereabouts known at all times, so they can be found for drug testing - is sure to stir up more debate.
U.S. Open semifinalist Yanina Wickmayer originally was given a one-year ban for violating that rule; she appealed, and the ban was lifted, but too late for her to be put in the Australian Open's main draw. So she had to go into the qualifying event and was left out of the Australian Open seedings on Thursday, even though she's ranked 16th.
-How good will Henin be?
Less than 10 days after Clijsters won the U.S. Open, the other Belgian woman who has been ranked No. 1 announced she would be returning, too, saying: ``A flame I thought was extinguished forever suddenly lit up again.''
The 27-year-old Henin has won seven Grand Slams and looked good in her first tournament back, beating 2008 French Open champ Ana Ivanovic and top-20 player Nadia Petrova. But then she lost to Clijsters in the final, and complained about a bothersome leg, so perhaps Henin will have to wait to make her mark. But it wouldn't be shocking to see her in a Grand Slam final this year.
``She doesn't look like she's been away from the game for a day, let alone 18 months,'' said TV analyst Darren Cahill, who used to coach Andre Agassi.
-What is the state of Sharapova's game, particularly her serve?
There are those who think Sharapova, a three-time Grand Slam champion and former No. 1, can return to the top - including Nike, which reportedly agreed to an eight-year contract extension with her.
But Sharapova is trying to fix her serve after shoulder surgery in October 2008: She double-faulted 21 times in her loss at the U.S. Open.
``I still believe,'' Cahill said, ``that someone like Maria Sharapova still has her biggest tennis ahead of her.''
-Should Federer and Nadal be worried?
For quite some time, Federer entered each January wondering whether that would be the year he'd finally win the French Open. He doesn't have to think about that any more, after completing a career Grand Slam in Paris last year. It was quite a 2009 for Federer, who also broke Pete Sampras' career record for major championships by claiming No. 15 at Wimbledon, reclaimed the No. 1 ranking, got married and became the father of twins.
Only five-set losses to Nadal in the Australian Open final, and to Juan Martin del Potro in the U.S. Open final, prevented a calendar-year Grand Slam for Federer.
``Now I want to stay No. 1 for as long as possible,'' he said.
And so Nadal is the one who needs to make a comeback - after having his 31-match winning streak at the French Open end; after pulling out of Wimbledon, citing sore knees; after losing to del Potro in the U.S. Open semifinals while hampered by a stomach muscle injury; after ceding the top ranking back to Federer.
All of 23, Nadal has given his body quite a beating already with his punishing style of play. Could that be catching up to him? Players such as del Potro, Andy Murray and Novak Djokovic will once again be trying to catch up to Federer and Nadal, who combined to win 17 of 18 major titles entering the 2009 U.S. Open.
-Can Andy Roddick win another Grand Slam title?
For so long the top American man in the game, the 27-year-old Roddick rededicated himself last season, with a new coach and new fitness regimen. The 2003 U.S. Open champ came close as can be to adding a second major trophy at Wimbledon in July, when he lost to Federer 16-14 in the fifth set of the final.
His serve and forehand allow Roddick to always be a contender for titles, especially on fast surfaces, and he might save himself some wear-and-tear by skipping Davis Cup this year.
``He's not blessed with Federer-like grace or talent. He's not blessed with the physicality of Nadal,'' Cahill said. ``But he's got a strong mind, and he keeps competing. He's the hardest worker out there, he's got a huge heart, and he's now putting himself back in a position to win these events.''
