World number one Victoria Azarenka stretched her unbeaten run to 24 matches this year with another easy win in her first appearance at the Sony Ericsson Open in Miami on Friday.

Her latest victim was Michaella Krajicek of the Netherlands, who fought hard but was no match for Azarenka as the Belarusian cruised to a 6-3 7-5 win.

Azarenka is off to the hottest start to a season since Martina Hingis won her first 37 matches in 1997. Her wins this year include the Australian Open and Indian Wells last week, but she realizes she now has a target on her back.

"I felt that she had nothing to lose, so she went for her shots, she was really aggressive," Azarenka told reporters.

"I think I could have been more aggressive and play more my game, but I found the right shot selection and the right opportunities when I needed."

Britain's Andy Murray, who was given a bye in the first round, rebounded from his early exit at Indian Wells last week to beat Colombia's Alejandro Falla 6-2 6-3.

The fourth seed faces a third-round clash with Milos Raonic, who defeated Arnaud Clement 7-6 6-2.

"I was expecting it to be tricky ... and managed to play better," said Murray.

"Once I settled down and started playing well, I was in most of his service games. So I was putting pressure on him."

American John Isner maintained his great run of form, which has included a win over world number one Novak Djokovic, by defeating Russian Nikolay Davydenko 2-6 6-3 6-4, highlighted by 10 aces.