10/06/2011 06:11 EDT | Updated 12/06/2011 05:12 EST

US gold medallist Merritt celebrates doping win, looks forward to London

ATLANTA - LaShawn Merritt was pessimistic about the chances of defending his Olympic title in London. The 400-metre champion figured it would be difficult to overturn a doping rule that banned him from the next summer games.

When his agent called Thursday morning, he expected the worst.

"I knew the ruling was coming out soon," Merritt said. "I didn't want to pick up."

But the Court of Arbitration for Sport threw out the IOC rule that bars any athlete who has received a doping suspension of more than six months from competing in the next summer or winter games. The court said the rule is "invalid and unenforceable" because it amounts to a second penalty, clearing the way for Merritt and dozens of other athletes around the world — as many as 50 in track and field — to compete in London.

Merritt completed his 21-month suspension in July after testing positive for a banned substance found in a male-enhancement product. In August, he finished second at the world championships in South Korea, but the IOC rule would have prevented him from running at the Olympics.

Now, he's back in the game.

"Today is a good day for me," Merritt said during a news conference arranged by his agent, Kimberly Holland, at a high-rise office overlooking downtown Atlanta. "To be able to go back and defend my title at the Olympic games, there's nothing better than that."

Holland first told her client that the CAS had ruled against him. Turns out, she was only kidding.

"It felt like when you're driving and the police pull up behind you. My heart dropped," Merritt said. "I was just laying in bed thinking, 'OK, I've just got to figure something out.'"

Then, she delivered the actual news. The ruling had gone in Merritt's favour.

He was stunned.

"For a couple of minutes, I was kind of in shock," Merritt said. "I got punked, but it's a good kind of punked."

Merritt, who also was 400 world champion in 2009, received a reduced suspension — the normal ban is two years — because he co-operated with authorities and was found to not have taken the drug to improve athletic performance.

The 25-year-old Virginia native insisted that he's learned a lot from the embarrassing situation.

"It was a little difficult," Merritt said. "It was a mistake. I was a young man. Mistakes happen. I'm just trying to keep that where it is and focus on moving forward."

Along with taking silver in his signature event at the worlds, he also helped the Americans win gold in the 4x400 relay at worlds. Merritt wasn't sure what he would've done in 2012 if he didn't have the Olympics for motivation.

"A lot of this sport is mental," he said. "Now, I just feel better. I feel better knowing I can move forward and defend my title and train hard and compete."

His coach, Dwayne Miller, expects Merritt's performance to improve now that he can start pointing to the Olympics again.

"Basically he was thinking after each race, what's next?" Miller said. "That burden is gone. Now he can focus on the Olympics. At one point, we didn't know what was next."

While serving his suspension, there were times when Merritt wondered if his athletics career was finished.

"It was tough to train for a long period of time without competing," he said. "Several times, I told my coach that I didn't want to train anymore. There were days I didn't want to get out of bed. There were days I felt like my career was over pretty much."

He credited his support system — parents, Miller and Holland — with helping him get through his lowest moments.

"Just them believing in me, having faith that one day everything would be fine, and here I am," Merritt said. "Overall, I'm a better person as far as not taking anything for granted. One day you can have something, and the next day it may be gone from a simple mistake."