Roger Federer, who missed an opportunity to win four straight majors twice in his career, in 2006 and 2007, when he was stopped by Rafael Nadal at Roland Garros after winning Wimbledon, the U.S. Open, and Australian Open titles consecutively, says the pressure on Novak Djokovic to try a similar feat at this year's French Open will be immense. "It's an amazing achievement in itself to win three in a row,' Federer said.