Serena reaches Doha semis; Venus stays alive

Serena Williams became the first player to clinch a spot in the semifinals of the Sony Ericsson Championships after beating Elena Dementieva 6-2, 6-4 Thursday for her third straight win in the group phase of the tournament. Williams was broken to trail 2-1 in the first set but then won seven straight games to take control of the match, moving the Russian around the court with her powerful ground strokes.