* Sharapova crushes American qualifier McHale (Adds Sharapova result, byline)
By Iain Rogers
MADRID, May 7 (Reuters) - World number one and defending champion Serena Williams continued her serene progress at the Madrid Open when she eased past Spanish wildcard Lourdes Dominguez Lino 6-2 7-5 in the second round on Tuesday.
Chasing a fourth title of the year and the 50th of her career, Williams had too much power for the slightly-built Dominguez Lino, who nonetheless managed to unsettle her illustrious opponent with some clever drop shots and lobs.
Williams was joined in the third round by Maria Sharapova after the Russian second seed thumped American qualifier Christina McHale 6-1 6-2 in Tuesday's night session.
Sharapova, a former number one who won her 29th career title in Stuttgart last month, will play Sabine Lisicki for a place in the last eight. The unseeded German upset 15th seed Dominika Cibulkova of Slovakia 7-6 7-6.
Williams, 31, said she had enjoyed the test against Dominguez Lino and the experience would stand her in good stead the next time she came up against a player like the 47th-ranked Spaniard, who likes to mix up her shots.
"I made a lot of errors, but her game kind of forces you to make errors," the American told a news conference. "It was a really good claycourt tennis match for me.
"Seeing as I have a few more tournaments on clay, it was perfect to play a match like this, so I know if I face another opponent like that I'll have that experience and I'll know how to play."
A 15-times grand slam singles champion, Williams will play unseeded Frenchwoman Kristina Mladenovic or 13th-seeded Russian Maria Kirilenko for a place in the quarter-finals. (Editing by Clare Fallon and Nick Mulvenney)