While more experienced half-marathon runners like Ryan Hall and Shalane Flanagan received most of the hype going into yesterday's ING Rock 'n' Roll Philadelphia Half-Marathon, two novices to the event emerged victorious.

In only his second half-marathon ever, Kenyan Matthew Kisorio finished first with a time of 1:00:15. The 21-year-old broke the course record of 1:00:27 set by Khalid Khannouchi in 1997. Despite the first-place finish Kisorio said he has room to improve.

"I'm very happy because that's my personal best and it's only my second half-marathon," Kisorio said. "But, I was trying to run under 1 hour. Maybe with this experience I will run better in my next race."

Coming in second was Ethiopian Gebre Gebremariam, who finished in 1:00:25. In the end, Kisorio's familiarity with Gebremariam, the defending World Champion Cross Country champion, pushed him, Kisorio said.

"I was worried [that he would catch me] but he's my friend," Kisorio said. "We've been competing in track events together for a while."

Arizona native Brett Gotcher was the first American to finish. Gotcher placed ninth with a time of 1:02:50.

Hall, the defending champion and the current recordholder for fastest half-marathon by an American, struggled en route to a 13th-place finish. Hall, from California, finished the event in 1:03:55.

Ethiopian Meseret Defar's performance was equally impressive. Running in her first half-marathon ever, Defar posted the top women's time of 1:07:44. Defar, who won an Olympic gold medal in the 5,000 meter event at Athens in 2004, set the record for fastest half-marathon run by a woman on American soil. The previous mark of 1:07:52 was set by Berhane Adere earlier this year.

Defar trailed for the majority of the race before taking the lead with about 2 miles to go. Her experience in speed events helped her make up the distance, she said.

"The last 100 meters were very close," Defar said. "My track speed helped me [break away from the pack]."

Defar said she did better than she expected considering her inexperience and the strength of the field.

"I was not expecting to win today because it's my first half-marathon," she said. "I didn't know what to expect this race, but when I started running, my legs felt good and I didn't get tired. I expected it to be harder for me."

Defar said that while she has considered running a full marathon, it's unlikely she'll do so any time soon.

"I'm excited now right now for the Olympics, where I'll be running the 5,000 meters," Defar said. "Maybe after that I will [start running full marathons]."

Kenyan Lineth Chepkurui finished second with a time of 1:07:46.

Flanagan, of Portland, Ore., who is the defending USA half-marathon champion and 2008 Olympic bronze medalist in the 10,000 meters, came in fourth with a time of 1:08:36.

The event featured nearly 19,000 participants from all 50 states and 15 countries. For full results, head over to philadelphia.competitor.com.