UPDATE 2-Tennis-Azarenka, 19, beats Serena to land Miami title

* First top-tier win for Belarussian teenager

* Williams's thigh heavily strapped

* American says she thought of pulling out (Updates with injury detail, quotes)

By Simon Evans

MIAMI, April 4 (Reuters) - Victoria Azarenka, the 19-year-old from Belarus, thrashed injury-hampered world number one Serena Williams 6-3 6-1 to win the Sony Ericsson Open on Saturday.

Williams, heavily strapped on her left thigh, never looked fully mobile and was comfortably beaten in 71 minutes by one of the rising talents in the women's game.

The victory, the first top-tier triumph for Azarenka, stopped the American claiming a record sixth title at Key Biscayne.

It was clear from the outset Williams was not 100 percent fit and she said she had considered pulling out of the final.

"I thought about it. I don't like to not play but I definitely thought about it. I thought the warmer I got the better I thought it felt," said Williams, who added she also had an ankle problem that further restricted her movement.