Key Biscayne:

Andy Roddick retired with a strained left hamstring in the first set on Wednesday, allowing Andy Murray to advance to the semi-finals of the Ericsson Open.

Murray became the first British to reach the Key Biscayne semi-finals since Tim Henman in 1998. The Scotsman is ranked a career-high 12th and leads the men’s tour with 23 wins — two against Roddick — in 27 matches.

No 14 Shahar Peer advanced to the semi-finals, beating No 24 Tathiana Garbin 6-0, 6-3. Serena Williams beat No 8-seeded Nicole Vaidisova 6-1, 6-4. The other women’s semi-final will be between top-ranked Justine Henin and Anna Chakvetadze. With second-ranked Maria Sharapova’s loss Wednesday to Williams, Henin is assured of remaining No 1 next week.