Watching Venus Williams matches, one you can see that she has more powerfull serve struck then any other players. For example, during her last match on Wimbledon Tour (Venus Williams vs. Agnieszka Radwanska (poland)) her average first serve struck speed was over 110 mph (177 km/h, 49.17 m/s) when Agnieszka Radwanska served with the average speed of 95 mph (153 km/h, 42.47 m/s). Williams fastest serve during the match was 122 mph (170 km/h, 54.54 m/s). Radwanska fastest serve – 104 mph (167 km/h, 46.49 m/s).
Venus Williams holds current women record for fastest serve struck in a main draw event. She recorded 130 mph (209.2147 km/h, 58.12 m/s) at the Zurich Open.
Other Venus Williams serve speeds (source: wikipedia.org)
2003 Australian Open quarterfinal – 125 mph (201 km/h), 2007 French Open second round, 2008 Wimbledon final, 2007 US Open first round – 129 mph. At Wimbledon in 2008, her average first serve speed was 115 mph (185 km/h) in the quarterfinal, 116 mph (187 km/h) in the semifinal, and 111 mph (179 km/h) in the final. She also had a higher average serving speed than then World No.1 Roger Federer as well as eventual men’s champion Rafael Nadal.