AMERICAN superstar sprinter Marion Jones will be among five leading Americans participating in the last two legs of the Engen Grand Prix Summer Series. Prevented by budget constraints from taking part in the March 13 Summer Series opening in Pietersburg, the Americans will be competing in Roodeport on March 19 and in Cape Town on March 26. In her last visit to South Africa, for the World Cup in Johannesburg in September, Jones blazed to the fastest 100m and 200m times of the year.