Agnieszka Radwanska swept aside by Li Na at Cincinnati Open

Top seed Agnieszka Radwanska has been knocked out in the quarter-finals of the Cincinnati Open in straight sets by Li Na.

The ninth seed broke instantly in what was a lengthy opening service game before going on to take the first 6-1 in just 28 minutes.

A break for the Chinese in the second was then followed by three saved break points as she held what was a pivotal game to take a 4-1 lead.

The former French Open champion then broke for a final time before serving out the contest 6-1.

Li's reward for defeating the number one seed is a semi-final encounter with Venus Williams.