iStockphoto/Thinkstock(BEIJING) -- Two-time Grand Slam champion Li Na announced that she is retiring due to reoccurring knee injuries on Friday.
Na was the first player from Asia to take home a major title.
"Most people in the tennis world know that my career has been marked by my troubled right knee," Li said in an open letter. "After four knee surgeries and hundreds of shots injected into my knee weekly to alleviate swelling and pain, my body is begging me to stop the pounding."
"After a few weeks of post-surgery recovery, I tried to go through all the necessary steps to get back on the court," the letter continued. "While I've come back from surgery in the past, this time it felt different.
"One of my goals was to recover as fast as I could in order to be ready for the first WTA tournament in my hometown. As hard as I tried to get back to being 100 percent, my body kept telling me that, at 32, I will not be able to compete at the top level ever again. The sport is just too competitive, too good, to not be 100 percent."
"I've succeeded on the global stage in a sport that a few years ago was in its infancy in China," Li concluded. "What I've accomplished for myself is beyond my wildest dreams. What I accomplished for my country is one of my most proud achievements."
Na hasn't played since losing in the third round at Wimbledon and withdrew from the U.S. Open due to a knee injury. Na won the 2011 French Open title and this year's Australian Open.
Andy Lyons/Getty Images(CINCINNATI) -- The Cincinnati Bengals are looking to go 3-0 for the first time since 2006 when they host the Tennessee Titans (1-1) on Sunday.
Cincinnati has a ten-game win streak at home headed into Sunday.
Quarterback Andy Dalton is well aware of the Titans defense. "They do a good job with different looks," Dalton said of the Titans defense. "We have to be sharp mentally to handle what they're going to throw at us."
Dalton hasn't thrown an interception or been sacked yet this year and credited the hard work of his offensive line.
"It's been a thing that we've really prided ourselves on," Dalton said. "It's one of our top goals, win the game, then no turnovers and then no sacks. We've done a good job of that obviously, so we've got to keep that going."
The Bengals will have a bye following their game against Tennessee on Sunday and will play the Patriots in week 5.
Elsa/Getty Images(NEW YORK) -- The New York Giants (0-2) hope to turn around a tough start to the season on Sunday against the Houston Texans (2-0).
"You treat every game as a must-win," Giants quarterback Eli Manning said. "You don't want to put any extra pressure on guys, but we know we've got to get things going. We have to start playing better football."
Giants head coach Tom Coughlin is well aware of Texans defensive end J.J. Watt, who also scored his first career touchdown in their win last week against the Raiders.
"He's a very good football player," Coughlin said of Watt. "Very energetic, they move him around, they play him in different spots, comes off the ball very well. There's no doubt people have to be aware of where he is."
Peter G. Aiken/Getty Images(SAN DIEGO) -- The San Diego Chargers (1-1) have a tough task at hand on Sunday when they travel to Buffalo to take on the Bills (2-0).
San Diego is coming off a big win against the Seattle Seahawks in week 2 and quarterback Philip Rivers understands this will be another challenge in a long season.
"It's going to be tough," Rivers said. "[They're] not a team we're overly familiar with and they've won two in a row. We got to go play good."
Chargers head coach Mike McCoy is doing everything he can to prepare his defense for stand-out rookie wide receiver Sammy Watkins.
"He's on his first go-around with each defensive back," McCoy said of the rookie. "He plays it for a little bit and as the game goes on he learns a few more things about the technique that guys trying to play. He's got so much to learn, but he's done a nice job the first couple weeks of the season, very explosive player."
Al Messerschmidt/Getty Images(EDEN PRAIRIE, Minn.) -- The Minnesota Vikings finally had enough with receiver Jerome Simpson.
Simpson was cut by the team Thursday, hours after ESPN reported the 28-year-old was cited on July 7 for misdemeanor charges of marijuana possession, driving on a limited license and having an open bottle in a motor vehicle.
While Simpson wasn't arrested, it is just the latest incident in which the receiver has been in trouble with the law.
Simpson pled guilty to a felony drug charge in March 2012 that resulted in a 15-day prison stint and three years of probation. He also was arrested for drunken driving last November, resulting in a three-game suspension to start this season.
Simpson played in 16 games last season for the Vikings, catching 48 balls for 726 yards and a touchdown.
Joe Robbins/Getty Images(FLORHAM PARK, N.J.) -- Many people are questioning whether NFL commissioner Roger Goodell should keep his job after the way he's handled the array of recent domestic violence charges against NFL players, but New York Jets quarterback Michael Vick isn't one of them.
"You have to give the man a chance," Vick said of Goodell. "You have to give him a chance, you have to give everybody a chance to get it right."
Vick went on to say that Goodell is doing a great job and that progress is being made.
"You see the other teams that are dealing with it now are making the right decisions, based on what has happened in weeks prior," he said. "You have to give people a chance. You have to give people a chance, man. You're not always going to get it right the first time."
In 2007, Goodell suspended Vick indefinitely after the quarterback pleaded guilty to federal dogfighting charges.
Vick was eventually reinstated by Goodell after missing two seasons.
Thinkstock(IRVING, Texas) -- Former Texas Rangers manager Ron Washington told reporters at a news conference Thursday that he resigned because of marriage infidelity.
“I was not true to my wife after 42 years,” Washington said. “I broke her trust. I’m here today to own that mistake and apologize to her and to those I disappointed.”
Washington stepped down as manager of the Rangers on Sept. 5, citing a personal issue. In eight seasons at the helm, he compiled a record of 664-611, leading them to two World Series appearances (2010, 2011).
Tim Bogar took over as manager on an interim basis.