"Maurice is right on track in the 100 metres," coach John Smith said in a statement. "Knowing his goals, I need him to completely focus on the 200 metres this weekend."

Greene has the fastest 100 metres time by an American this year (9.94 seconds). He had earlier said he wanted to compete in one round of the 100 at the U.S. championships at Stanford University which begin on Thursday "just to give people a show".

Now he will run only the three rounds of the 200 at the meeting, which serves as the American qualifier for the world championships in Paris.

Greene will receive an automatic berth in the U.S. team as the defending world 100 metres champion but must finish in the top three at Palo Alto to be eligible for the 200.

He won both the 100 and 200 metres at the 1999 world championships but competed in only the 100 metres at the 2001 championships in Edmonton, an event he won.