Countdown to Rio: Storylines to watch

The 2016 Summer Olympics will likely be Usain Bolt's last. Paul Gilham/Getty Images

The 2016 Summer Olympics in Rio de Janeiro are two years out from Tuesday. Here are some early storylines to keep on the radar:

Michael Phelps: Will he or won’t he?

After retiring from swimming following the 2012 London Games, the most decorated Olympian of all-time is back in the pool. But will the 29-year-old Phelps add to his 22-medal total? Since returning to competitive races, he has been careful to say what his Olympic intentions are, so the Phelps Watch continues. In the meantime, he will compete in four events at this week’s U.S. Championships.

Brazil as host

The success of the World Cup boosted some morale within the International Olympic Committee that Rio de Janeiro could host a large sporting event like the Summer Games. A special task force was assembled to keep an eye on the project and address concerns on the preparations. On Monday, a Brazilian newspaper estimated that while only 25 percent of construction is competed, workers remain on schedule.

Usain Bolt’s treble-treble

The Jamaican world-record holder looks to become the first runner to win three gold medals in three consecutive Olympics. Bolt is carefully mapping out his road to Rio, as a foot injury has sidelined him for most of the 2014 season. He won three gold medals at the 2013 IAAF World Championships in Moscow and will use 2015’s edition in Beijing as a lead-up to his final Summer Games. Bolt has also said he aims to better his world record in the 200 meters before retiring.

Kerri Walsh Jennings back for more

After three consecutive beach volleyball gold medals with Misty May-Treanor by her side, Kerri Walsh Jennings looks to make her fifth U.S. Olympic team. She is now partnered with April Ross and has moved to the right side of the sand in the transition. Ross and playing partner Jennifer Kessy lost to May-Treanor and Walsh Jennings in the all-American final at the London Games.

Winning streaks for women

Walsh Jennings isn’t the only woman looking to continue her Olympic winning streak in Rio. In London, Kim Rhode became the first American athlete to win five medals in an individual event in five consecutive Olympics after locking up another gold in women’s skeet. The U.S. women’s basketball team also will vie for a sixth consecutive gold medal and ninth overall. After the U.S. rowing team won its second gold in the women’s event, it won team titles at the 2013 World Rowing Cup in Lucerne and 2013 World Rowing Championships in Chungju, South Korea.

Brazil’s ‘Blade Runner’

Before dominating the legal headlines, Oscar Pistorius inspired millions of people in 2012 when he became the first amputee athlete to compete in a Summer Olympics. What many don’t remember is Pistorius losing to Brazilian sprinter Alan Oliveira in the 200-meter dash in the subsequent Paralympic Games. If Oliveira manages to make the Brazilian national team, he could become the star of the Olympics. He will be 23 by then and has been bettering his personal bests at a fast rate. Could he become a medal threat? Will the IAAF backtrack on the blade rules if this happens? Time will tell.

Gabby Douglas to defend?

Douglas has enjoyed life as a celebrity since winning the all-around gymnastics gold medal and helping the U.S. team win the Olympic title in London. She recently left coach Liang Chow for a second time and is now training with Kittia Carpenter in Columbus, Ohio. Douglas recently told The Associated Press that she will not compete until 2015 so she can work on new routines with Carpenter.

NBA debate

The U.S. men’s basketball team has won 14 Olympic gold medals. Will its quest for No. 15 be without NBA stars? Indiana Pacers forward Paul George suffered a serious leg injury in a team scrimmage last week, igniting the debate over whether stars should compete in international tournaments. Marc Cuban has been a longtime critic of FIBA and its relationship with the NBA. For now, NBA commissioner Adam Silver said he does not anticipate any major shift in participation by the league’s players.

Golf and rugby return

Golf’s Olympic qualifying window is now open. The sport returns to the Olympic program for the first time since 1904. Sixty golfers will qualify in each of the men’s and women’s events -- a 72-hole stroke-play tournament -- based on the world rankings.

The rugby sevens format will make its debut on the Olympic stage, a faster style of play in comparison to the 15-a-side style last seen on the program in 1924.

Yes, mascots

London’s mascots were two drops of steel with cameras for eyes to honor the start of the industrial revolution. The Rio Olympic Committee is currently fielding a selection process with public input from Brazilian animators, designers and filmmakers. The mascot will be revealed in late 2014.