Panettiere was spotted shopping in Beverly Hills while the IBF, IBO and WBO heavyweight world champion was off training for a heavyweight showdown with David Haye on July 2 in Germany, the Daily Mail reported.
He was recently featured in the documentary "Klitschko," which followed the boxing careers of him and his brother Vitali Klitschko.
Since then, she has gone on to appear in many feature films and TV movies.
During her time on "Heroes" she dated her co-star Milo Ventimiglia from December 2007 to February 2009.
That same year she began dating Ukrainian heavyweight boxing champion Wladimir Klitschko but she announced in May 2011 that they had split up.
She departed the show temporarily in October 2015 to seek treatment for postpartum depression and returned to the set in early January 2016.
She admitted herself for more treatment after filming on Season Four concluded.
"I have a lot of respect for Hayden as a person and as a friend, and I believe we'll keep our friendship even after the separation." Really? Also, we think by "long distance" he also meant the glaring height difference between him and the petite actress.
He towers at 6-foot-6, while she hovers at 5-foot-2.
Following Connie Britton's departure from the show after the first half of Season Five, Hayden gained top billing among the main cast.
The controversial heavyweight champion revisited some familiar, abhorrent themes in an interview with Sports View London, in which the bigoted Brit suggested that...
The "Scream 4" actress, 21, and Klitschko, a Ukrainian boxing champ who, at 35, is 14 years her senior, said that the long-distance thing just wasn't working out.