Olympic 200m champion Allyson Felix withdrew before the 100m semifinals Friday at the U.S. Championships, her only event at the Sacramento, Calif., meet.
Felix tied for 14th overall in the 100m preliminary heats Thursday at 11.53 seconds to be among 16 women advancing.
She did not appear to be a favorite to win the U.S. title after she said before the meet she wasn’t all the way back from a torn hamstring suffered at the 2013 World Championships.
[WATCH LIVE: U.S. Championships, Friday at 10 pm ET]
“My speed is struggling, and I don’t have the turnover that I typically have,” she said, according to The Associated Press. “I’m hoping by the end of this season I’m able to produce some really great times. I’m hoping that August is really a time that I can peak. We’ll see if it goes according to plan or not.”
Felix did not enter her signature event, the 200m, at the U.S. Championships.
Very pregnant Alysia Montano runs at U.S. Championships
Puma has introduced the “BeatBot,” a self-driving, line-following robot that runners can program to move at a specific pace around a track.
That means one could race against a robot-version of Usain Bolt‘s 100m world record of 9.58 seconds, with BeatBot’s top speed at just over 27 miles per hour.
The BeatBot can also navigate track curves, as shown in the video above.
Puma plans to roll out BeatBot to various track programs around the world over the year.
MORE: Bolt, Ashton Eaton set for showdown
Several U.S. Olympic champions highlight the Penn Relays and Drake Relays fields, live on NBCSN and NBC Sports Live Extra on Saturday.
At the Penn Relays in Philadelphia, the U.S. 4x100m, 4x200m and 4x400m pools include:
Justin Gatlin: 2004 Olympic 100m champ
Tyson Gay: Olympic 100m, fourth place
Carmelita Jeter: Olympic 100m silver medalist
Jeremy Wariner: 2004 Olympic 400m champ
Sanya Richards-Ross: Olympic 400m champ
Also competing will be two-time Olympic 100m champion Shelly-Ann Fraser-Pryce, 2008 Olympic 100m silver medalist Kerron Stewart and 2015 World 200m silver medalist Elaine Thompson for Team Jamaica.
STREAM: Penn Relays: 12:30-3 p.m. ET
Next is the Drake Relays in Des Moines, Iowa, including:
- 2008 Olympic champion LaShawn Merritt versus 2012 Olympic champion Kirani James in the 400m
- World Indoor champion Vashti Cunningham in the high jump. Cunningham, 18, is the daughter of retired NFL Pro Bowl quarterback Randall Cunningham.
- 2008 Olympic champion Dawn Harper-Nelson versus 2013 World champion Brianna Rollins in the 100m hurdles.
STREAM: Drake Relays: 3-5 p.m. ET
MORE: Full NBC Olympic trials broadcast schedule