NFL sacks champion Robert Mathis admits he made a mistake late last season. Now it's going to cost him -- four games and four paychecks.

The Indianapolis Colts' career sacks leader was suspended Friday for violating the league's ban on performance-enhancing substances. What exactly Mathis tested positive for remains a mystery, but the linebacker said he was seeking fertility assistance. He added he and his wife are expecting a baby.

"I hope my fans will understand the unique circumstances involved here and continue to know that I am a man of integrity," he said in a statement.

Mathis set a Colts' record with 19½ sacks in 2013. In 11 NFL seasons, he has 111 sacks.

  • The 49ers signed sixth-round cornerback Kenneth Acker of SMU to a four-year deal.

  • Minnesota signed former Stanford guard David Yankey, a fifth-round draft choice. Former Cardinal linemate Cameron Fleming, a fourth-round pick, signed with New England.

  • Authorities in Miami say they found insufficient evidence to file sexual assault charges against former NFL safety Darren Sharper. He is being held in Los Angeles on sexual assault charges and is being investigated in Louisiana, Arizona and Nevada.

    Swimming

    For the first time since his supposed farewell at the 2012 London Olympics, Michael Phelps was on top of the podium. He won the 100-meter butterfly at the Charlotte (North Carolina) Grand Prix, while rival Ryan Lochte watched, a brace on his injured knee. Phelps also qualified for the 200 freestyle but limited himself to one race in the evening. He finished in 52.13 seconds, a half body-length ahead of Pavel Sankovich. Conor Dwyer took the 200 free. Phelps plans to swim at Santa Clara in late June.

    WNBA

    Cappie Pondexter had 17 points and New York beat Connecticut 75-54 in the opener for both teams. Former Stanford star Chiney Ogwumike, the first overall pick of the draft, had 13 points and five rebounds for the Sun.

  • Candace Parker had 18 points, and Los Angeles beat Seattle 80-69. Sue Bird, returning to Seattle after missing last season to have a cyst removed from her knee, had seven points and four assists.

  • Maya Moore had 34 points and nine rebounds as defending champion Minnesota beat Washington 89-77.

    Soccer

    Jill Ellis was named the U.S. national team coach in the run-up to the women's World Cup next summer in Canada and beyond. Ellis had been the interim coach since Tom Sermanni was fired in April.

  • It's "a mistake" to hold the World Cup in the searing summer heat in Qatar and the 2022 event "more than likely" will be moved to winter, FIFA president Sepp Blatter said.

  • Constructors say the roof of Sao Paulo's Itaquerao stadium, which will host the World Cup opener between Brazil and Croatia on June 12, won't be completed until the tournament is over.

    Tennis

    Rafael Nadal beat Andy Murray 1-6, 6-3, 7-5 and secured a spot in the Italian Open semifinals in Rome. Murray won the first set in 37 minutes, but Nadal broke early in the second and took control with a late break in the third. Serena Williams beat Zhang Shuai 6-1, 6-3 in women's play.

    Motor sports

    Clint Bowyer won the Sprint Showdown to advance to the $1 million All-Star Race. AJ Allmendinger was second to also advance to Saturday's main event at Charlotte (North Carolina) Motor Speedway. In fan voting, Josh Wise upset Danica Patrick to earn a spot in the race. Kyle Busch led 130 of 134 laps in winning the NASCAR Truck Series race at the 1.5-mile track.

    Hockey

    Seth Jones scored in overtime, and the U.S. ended a two-game losing streak by beating Kazakhstan 4-3 at the world championships in Minsk, Belarus.