American Maurice Greene confidently predicted on Thursday that he will retain his Olympic 100 metres sprint crown and bring gold home from Athens.

"Do I need another gold? I wouldn't say I necessarily need it but I'm going to get it," Greene said ahead of Friday's Zurich Golden League meeting, where he will finalise preparations for the Games.

Greene has suffered defeats in his two races on European soil in the past two weeks after being beaten by Portugal's Francis Obikwelu in the Paris Golden League meeting and by Jamaican Asafa Powell in London.

The Olympic champion blamed both defeats on poor starts and said he is ready to return to winning ways in Zurich after curing problems with specific training over the past week.

"I have a little problem I have to work out and this race will tell me if I have worked those problems out," said Greene, who will also run in a 4x100 metres relay in Munich on Saturday before heading to Athens.

"I'm working on the start of my race and I think we are getting close to it.

"I need a lot of improvement on my start. It needs to be efficient, which it hasn't been.

"The strongest part of my race is the middle and the end and it is getting to that part that has been the problem. I haven't been able to come out of the blocks and run straight.

"This has happened because over the last couple of years we've changed so many things because I was injured.

"I think I am close (to getting the start right) now. We'll see tomorrow night."

NUMBER 50

Greene will go head-to-head with Powell, Obikwelu and world champion Kim Collins of St Kitts and Nevis at the Letzigrund. Of the leading sprint names, only American Shawn Crawford, the fastest man in the world this year, is absent.

Greene, 30, said: "I'm looking for my 50th (career) sub-10 second race. Who can say that?

"I'm not a person who looks at stats. They've just pointed out to me that the next one will be number 50 and I sat in my room thinking that is a lot."

Regardless of the outcome in Zurich, Greene is convinced sprint gold will be his in Athens.

He has an affinity with the Greek capital after winning the first of three world titles there in 1997 and setting the previous world record of 9.79 seconds two years later.

Greene predicted that Collins will not have the speed to follow up his world title with an Olympic gold and said he believes 21-year-old Powell cannot match him for pace.

"He (Powell) is a good runner," Greene said. "He is young and he is going to be around a long time.

"He is very strong and very powerful and we are going to have some great races.

"But how much faster can he run? That (a 9.8-second race) ain't fast enough. It has got to be faster than that.

"I've already been there. I'm trying to go somewhere I've never been.

"If I put my right race together that won't be fast enough."

The 100 metres world record is currently held by American Tim Montgomery, who shaved one-hundredth of a second off Greene's best effort in Paris two years ago.

However, Montgomery failed to qualify for Athens.