Sharapova still no match for Serena – even on an off-day

World No 1 overcomes error-strewn and lethargic display to crush peak-form rival

The standards Serena Williams sets herself are such that even tournament titles are sometimes not enough. When the world No 1 analysed her 4-6, 6-3, 6-0 victory over Maria Sharapova in the Miami final on Saturday it was as though she was talking about a defeat.

"Today wasn't my day," Williams said. "Maria played the best I have seen her play. She was moving unbelievably well and hitting winners from everywhere. After the first set I had more than 20 unforced errors and I just thought: 'Why am I playing like this?'

"How did I end up winning when I actually wasn't on top of my game? I need that tape so I can go home and study it and train and try to get better," she added.

"I was making so many errors. I was like: 'Serena, are you really going to get to the final and not play up to your potential?' I don't think I was as energised as I could be. I don't think I had enough energy. I think I may have done too much work yesterday, may have hit too long and done too much gym."

Nevertheless, a lethargic and error-prone Williams was still too good for Sharapova, who had won her previous 11 matches. After taking advantage of Williams' mistakes in the first set, and ending a run of 13 successive lost sets to the American, Sharapova was outgunned and outclassed. She lost the last 10 games as she went down to her 11th defeat in a row to Williams .

Sharapova has yet to win the Miami title, despite appearing in five finals, while Williams became only the fourth woman in the Open era – after Martina Navratilova, Chris Evert and Steffi Graf – to win the same Women's Tennis Association tournament on six occasions.

When Williams reclaimed the world No 1 ranking in February she insisted she would not chase ranking points in defence of the position. The likelihood is that she will not need to. This was only her second tournament since the Australian Open, but she will strengthen her position at the top of the rankings in today's updated list.

Williams is likely to increase her lead over Sharapova, the world No 2, by the end of the French Open. While Sharapova has a mountain of points to defend on clay, Williams has comparatively few, especially at Roland Garros, where she lost in the first round last year. Victoria Azarenka, the world No 3, is the only other immediate threat and the Belarusian also has a substantial number of points to defend in the coming weeks, especially at the start of the clay-court season.