Rio de Janeiro’s biggest challenge in hosting the 2016 Games will be quelling the murderous violence that has plagued its slum neighborhoods for years. Recent warring among rival drug crews left more than 40 dead and sent a police helicopter down in flames only a mile from the Maracana stadium where the opening ceremonies will be held. “We never hid our problems during the bid process,’’ says Mayor Eduardo Paes. “We still have a lot to do, we have a long way to go.’’ . . . NBC Universal Sports chairman Dick Ebersol thinks it’s silly for the USOC to hire a search firm to find a chief executive officer to replace Stephanie Streeter by year’s end, saying that it would “just come up with washing machine manufacturers and insurance agents.’’ The better option, he says, would be to name a CEO from one of the national sports bodies like gymnastics or swimming. That’s what the committee did after its last failed experiment with a corporate outsider, naming former USA Wrestling chief (and former Olympian) Jim Scherr, whom the board pushed out in March . . . Even with only one international veteran, the US women’s gymnastics team had a terrific showing at the World Championships in London, going 1-2 in the all-around and medaling in three of the four apparatus events. Bridget Sloan, the only Olympian on the squad, and Rebecca Bross matched Chellsie Memmel’s and Nastia Liukin’s 2005 sweep, and Kayla Williams, who was still at the sub-elite level when the year began, became the first American to win the vault. Nothing for the US males, whose top contender, Jonathan Horton, had a rough meet, finishing 17th in the all-around and last on the horizontal bar, where he won silver in Beijing. “I’ll be better for it,’’ Horton vowed. Though the Chinese didn’t medal in either all-around, they cleaned up elsewhere, winning six of the 10 event finals and nine medals overall.

Defending champion Paula Radcliffe will be favored to win her fourth women’s title and Marilson Gomes dos Santos his third men’s crown in Sunday’s New York City Marathon. Radcliffe, who skipped last summer’s global marathon in Berlin while rehabbing from foot surgery, will be up against Boston victor Salina Kosgei, while Santos will take on two-time victor Martin Lel, two-time world champ Jaouad Gharib, former winner Hendrick Ramaala, four-time Boston titlist Robert Cheruiyot, and Americans Ryan Hall, Meb Keflezighi, Brian Sell, and Abdi Abdirahman. If a Yank wins, it’ll be the first time since Alberto Salazar in 1982. To mark the 40th running of the race, the New York Road Runners have named the top marathoners from each decade: Bill Rodgers and Miki Gorman from the ’70s, Salazar and Grete Waitz from the ’80s, German Silva and Tegla Loroupe from the ’90s, and Gomes and Radcliffe from the 2000s. Rodgers, who last competed in the Apple in 1988, and old friend Frank Shorter will run the last few miles of the race along with George Hirsch, the NYRR’s 75-year-old board chairman. Joan Benoit Samuelson will run the whole route to celebrate the 25th anniversary of her Olympic gold medal in Los Angeles . . . US taekwondo fighter Steve Lopez may have fallen short with a Beijing bronze after two Olympic golds but he ruled the planet again at the World Championships in Copenhagen, winning his record fifth title, while brother Mark’s bronze was his fourth career medal. Danielle Pelham contributed a women’s gold . . . The Olympic flame, which was kindled in Greece last Thursday, begins its trek across Canada Friday, starting in Victoria, British Columbia, and ending in Vancouver for the opening ceremonies Feb. 12, with 12,000 torchbearers taking part in the longest domestic relay (45,000 kilometers) in history.

The US and German women’s soccer teams, which missed each other at both the 2007 World Cup and 2008 Olympics, will play for the first time in nearly three years tomorrow at the new Impuls Arena in Augsburg, one of the sites for the 2011 Cup. It will be the first time the US has played in Germany since 2000. It’ll be the 25th meeting between the old rivals, with the Americans holding a 16-4-4 edge . . . The soccer teams representing Great Britain at the 2012 Games in London will be all-English, since the other three countries - Scotland, Wales, and Northern Ireland - have opted out rather than jeopardize their separate status within FIFA, the global federation. It’ll be the first time the UK, which won three of the first four Olympic men’s gold medals, has had a team at the Games since 1960 . . . Evgeni Plushenko’s easy victory in last weekend’s Grand Prix event in Moscow after three years away from international competition says as much about the state of men’s figure skating as it does about the defending Olympic champion, who was summoned back because the Russians didn’t have a contender after winning the last four gold medals. Plushenko, who turns 27 next month, still has enough game left despite his creaking knees to be a contender in Vancouver. World champ Evan Lysacek, who’s hoping to break a 22-year American drought at the Games, makes his season debut at this weekend’s Cup of China in Beijing, along with Wakefield’s Stephen Carriere, who won the silver there last year.

The Chad-and-Shani Show is revving up for another boffo Olympic year, with Chad Hedrick and Shani Davis qualifying for a combined seven events on the World Cup speedskating circuit as well as the team pursuit. “These guys around the world are going to deal with us just like last time,’’ declared Hedrick, who won a medal of each color in Turin, to go with Davis’s gold and silver. Seven members of the 2006 team will be in contention for Vancouver spots, including Tucker Fredricks, Jennifer Rodriguez, Elli Ochowicz, Catherine Raney, and Maria Lamb, plus 2002 member Nick Pearson . . . Only five of the 15 members of the US luge team for the World Cup season will be determined at the trials, which conclude in Park City, Utah, next week. Already given byes based on last year’s performances are Tony Benshoof, new citizen Bengt Walden (Westborough), world champion Erin Hamlin, Julia Clukey (Augusta, Maine), and all three men’s doubles: Mark Grimmette-Brian Martin, Christian Niccum-Dan Joye, and Matt Mortensen-Preston Griffall. Five women are in the chase for three spots: Ashley Walden (Westborough), teenagers Emily Sweeney (Suffield, Conn.) and Kate Hansen, Megan Sweeney, and Courtney Zablocki . . . No surprises among the pilots for the US bobsled team for the World Cup season: world champion Steve Holcomb, Todd Hays, and John Napier on the men’s side, and Shauna Rohbock, Erin Pac, and Bree Schaaf on the women’s. The pool of pushers includes Melrose’s Steve Langton. Noelle Pikus-Pace easily won the women’s skeleton trials and will be joined by Rebecca Sorensen and Katie Uhlaender, who was given a medical waiver since she’s rehabbing from multiple surgeries after shattering a kneecap last April in a snowmobiling accident. Zach Lund leads the men’s team, which includes Eric Bernotas (also on a waiver) and, surprise, John Daly.