On the men's side, qualifier Guillermo Canas [ Images ], who last week ended world number one Roger Federer's [ Images ] 41-match winning streak, beat experienced Briton Tim Henman [ Images ] 3-6, 6-2, 6-1.

Williams, playing for the first time since winning in Memphis last month, produced 31 unforced errors in the first set before overwhelming her 88th-ranked opponent.

"At four-love I was thinking hold, break, hold, it's even," Williams told reporters. I felt really confident.

"I didn't feel like it was a set for me to lose. It was definitely a set I could win, just keep some balls in."

The American improved to 34-5 at the tournament which she won in 1998, 1999 and 2001.

Top seed Maria Sharapova [ Images ] will begin her campaign against 93rd-ranked Yung-Jan Chan of Taiwan who beat Nuria Llagostera Vives of Spain 6-2, 6-3.

Sharapova, last year's runner-up at Crandon Park to fellow Russian Svetlana Kuznetsova [ Images ], lost in the fourth round of the Pacific Life Open last week.

In other first-round matches, Dutch teenager Michaella Krajicek, beaten last week by Sharapova, advanced to face Czech eighth seed Nicole Vaidisova [ Images ] with a win over Georgian Anna Tatishvili 6-3, 7-6.

Frenchwoman Emilie Loit knocked out last week's surprise package Sybille Bammer of Austria 2-6, 6-3, 6-1.

Austrian Bammer, the only mother in the world's top 50, beat former world number one Serena Williams [ Images ] in Hobart this year and lost in the Pacific Life semi-finals to Kuznetsova.

Argentine former world number eight Canas continued his comeback after serving a drugs ban by handing Henman his third defeat in a row.

Henman, 32, was playing in Miami [ Images ] for the 12th year in a row and reached the 1998 semi-finals. He was competing in only his third event of the season after overcoming a knee injury.

American Vince Spadea defeated compatriot Robby Ginepri 6-1, 6-3 and Frenchman Sebastien Grosjean eliminated former French Open [ Images ] runner-up Martin Verkerk of the Netherlands 6-3, 6-4.

Two Americans advanced, youngster Sam Querrey beating Russian Igor Andreev 5-7, 6-2, 6-4 and Kevin Kim ousting German Benjamin Becker 6-4, 3-6, 6-2.