Australian Open: Seven stories to follow

    Story highlights

    • The Australian Open starts Monday in Melbourne
    • Rafael Nadal makes his grand slam comeback
    • Serena Williams seeks a 19th career major
    • Roger Federer enters with momentum after 1,000th win

    (CNN)A year ago at the Australian Open, Stan Wawrinka achieved something not done in five years. He became the first man outside tennis' "Big Four" to win a major since Juan Martin del Potro in 2009.

    The women's champion was less surprising, in the form of the now retired Li Na.
      With this year's opening grand slam starting Monday, here are seven things to watch as the tennis season bursts into life.
      Rafa's comeback
      If Rafael Nadal wins in Melbourne, he might cherish his second title more than his first.
      That's because after beating Roger Federer in a thrilling five-set final in 2009, Melbourne Park has been less than kind to the 14-time grand slam champion on the health front.
      Check out this list: In 2010 he retired with a knee injury, a year later he suffered a hamstring injury in his quarterfinal and last year a back problem surfaced while warming up for the final.
      It was the clear turning point and Wawrinka took advantage. It was his long-time rival Federer who wept after losing to Nadal in 2009, but it was the Spaniard's turn to cry in 2014.
      Nadal hasn't competed at a grand slam since Wimbledon, having skipped the U.S. Open with a wrist complaint, and his buildup has been marred by two bad losses in the Middle East.
      But Friday's draw for 2015's first major was kind to Nadal. He appears to have a smooth path to the semifinals.
      Should Nadal somehow be the last man standing, only two triumphs would separate him and 17-time grand slam winner Federer.
      The man from Manacor
      The man from Manacor

        JUST WATCHED

        The man from Manacor

      MUST WATCH

      The man from Manacor 05:47
      Serena's quest for 19
      If it was an odd-numbered year over the last decade, chances are that Serena Williams won the Australian Open. She took home the title in 2003, 2005, 2007 and 2009.
      But Williams' recent appearances mirror Nadal's.
      There was the ankle she hurt at a warm-up tournament in 2012 that led to a fourth-round exit in Melbourne. In 2013 a back injury was probably to blame for a quarterfinal loss and last year the back flared up again in the quarterfinals.
      Williams' play early in 2015 is sure to have worried her fans, too. The 18-time grand slam singles winner complained of a lack of energy at the Hopman Cup in Perth and subsequently split two of her four singles matches.
      Like Nadal, Williams' longest grand slam drought now happens to be in Melbourne.
      She won the U.S. Open in September by topping her BFF, Caroline Wozniacki, but they can't face off in the Australian Open final since they're in the same quarter.
      Serena Williams:  Standing with Giants
      Serena Williams:  Standing with Giants

        JUST WATCHED

        Serena Williams: Standing with Giants

      MUST WATCH

      Serena Williams: Standing with Giants 04:12
      Roger's bid for one more major
      With Nadal's performances patchy, world No. 1 Novak Djokovic getting off to a less than stellar start in 2015 and Andy Murray struggling for grand slam form, the 33-year-old Federer can't be discarded.
      While Federer didn't have to face any of his fellow "Big Four" members as he shone in Brisbane -- where he collected his 1,000th match win -- he defeated two players thought of as outside grand slam contenders in 2015.
      He dispatched Milos Raonic in the final having routed Grigor Dimitrov in the semifinals.
      Aiding Federer would have been a kind draw, but unfortunately for him, it didn't happen. He found himself in the same quarter as Murray and same half as Nadal.
      Federer's quest for a missing title
      Federer's quest for a missing title

        JUST WATCHED

        Federer's quest for a missing title

      MUST WATCH

      Federer's quest for a missing title 06:11
      Eugenie Bouchard and the Genie Army
      Can the "Genie Army" propel Eugenie Bouchard to glory?
      Although she showed flashes in 2013, last year in Melbourne was when the tennis world truly took note of the 20-year-old.
      Her semifinal showing wasn't an anomaly, with Bouchard then reaching the last four at the French Open and the final at Wimbledon.
      But Bouchard couldn't duplicate her success from August onwards, the low point perhaps coming at the year-end championships where she failed to win a set in her three matches. Fatigue no doubt played a role.
      Bouchard arrives in Melbourne this year without a permanent coach, and you wonder how high her confidence is.
      The return of Juan Martin del Potro
      Only The Grinch wouldn't be happy that del Potro is back playing tennis.
      Skipping most of last year with further wrist troubles, his supporters must have been holding their breath when the Argentine pulled out of Brisbane.
      But he returned in Sydney this week -- unsure of how his left wrist would cope -- and made the quarterfinals. The pain hasn't gone away yet, he said.
      None of the contenders would want to face del Potro early, though only the very optimistic would suggest he could win a second major over the coming fortnight.
      Maybe claiming a few rounds and coming through the tournament unscathed would be enough for him.
      He doesn't face a top-10 player in his opener but it's still an enticing -- and imposing -- encounter. The 6-foot-6 "Tower of Tandil" plays 2013 Wimbledon semifinalist Jerzy Janowicz, who stands 6-foot-8.
      Simona Halep's opening major?
      In an era where players on the women's tour all seem to be towering 6-footers, Simona Halep -- 5-foot-6 -- is an exception.
      She still packs a punch from the baseline, but it's her use of angles that so often gets her into winning positions in rallies. Her backhand is one of the best around.
      If Halep's breakthrough was in 2013, she went one better last year by making the difficult jump into the top 10 and top five.
      How close was the Romanian to winning the French Open? Very. She extended one of the game's top competitors, Sharapova, to 6-4 in the third set of the final.
      Halep -- the most clicked on player on the WTA's website last year -- began this year with a title in Shenzhen.
      French Open outsider's meteoric rise
      French Open outsider's meteoric rise

        JUST WATCHED

        French Open outsider's meteoric rise

      MUST WATCH

      French Open outsider's meteoric rise 01:10
      A high-profile home hope
      Who is the top Australian hope?
      The rankings will tell you it's Samantha Stosur, who like del Potro is a U.S. Open winner. She's the world No. 20 on the women's tour.
      But Stosur has never really flourished at the Australian Open, and she hasn't been shy to admit that nerves have been a huge factor. Only once since 2007 has Stosur -- armed with arguably the best second serve in the women's game -- exceeded the third round.
      Australians are probably banking on Nick Kyrgios, the athletic 19-year-old who stunned Nadal at Wimbledon, to have an extended run.
      Kyrgios chose to take a break in September, saying he was "burnt out," and injuries have crept up. He missed the Hopman Cup with a sore back. So expecting too much from Kyrgios may be a mistake.