"When you know he's hurting, all you want to do is deliver that knockout blow" - When Novak Djokovic retired at Australian Open against Andy Roddick

Novak Djokovic came into the 2009 Australian Open as the defending champion, and was among the favorites to win the tournament, alongside the likes of Roger Federer, Rafael Nadal and Andy Murray. Unfortunately, the tournament ended disastrously for the Serb.

The No. 3 seed in the tournament, Djokovic reached the quarterfinals, where he took on former US Open champion Andy Roddick. Starting exceptionally, he took the opening set in the tiebreaker and looked on course for victory. However, as the match progressed, the 24-time Grand Slam champion's physical fitness started going away under the heat of the Melbourne sun.

That, combined with the stress of defending his maiden Grand Slam title started weighing on the Serb, who went on to lose the next two sets. In the fourth set, after a 10-minute medical timeout, he finally threw in the towel and retired from the match.

Speaking at his press conference after the 6-7(3), 6-2, 6-2, 2-1 win, Roddick spoke about his opponent's decision, admitting that he could see he was struggling in the conditions.

Roddick insisted that it was important to deliver the knockout blow in such cases, instead of wondering whether the opponent would retire or not. The American, although sad to see Djokovic retire without finishing the match, was happy that he got away with the win at the end of the day.

"Obviously you know he's hurting. When you know he's hurting, all you want to do is just deliver that knockout blow," Roddick said.

"You don't want to keep playing the game of wondering if he's going to do it or not, or if he's close. Only he really knows. At that point, you don't want to see anybody go out, but I was happy that I was able to get the last break in there, the last blow," he added.

"People could see I was struggling with movement" - Novak Djokovic on his Australian Open retirement

Tennis - Australian Open - Source: Getty

Speaking about the retirement himself, Novak Djokovic told the press later on that he felt cramping and soreness in his body. The Serb admitted that he tried to keep playing on, but couldn't do enough to fight his body for as long as it was necessary.

"The main reason is cramping and soreness in the whole body. I think the people could see that I was struggling with movement. I really tried my best but sometimes you can't fight against your own body."

"I didn't have any big pains in any particular muscles or parts of the body. It was general soreness," Djokovic said.

Roddick went on to lose in the next round to Roger Federer, who then lost in the final to Rafael Nadal.