At the 2010 French Open, Serena and Venus Williams completed four straight major doubles titles.
Their run began at Wimbledon in 2009, continued at the 2009 US Open and 2010 Australian Open, and reached four consecutive major championships when they won Roland-Garros in 2010. They defeated Květa Peschke and Katarina Srebotnik 6–2, 6–3 in the final.
The achievement is sometimes confused with a calendar-year Grand Slam, which requires winning all four majors in the same season. The sisters’ streak crossed two seasons, so it was a non-calendar-year Grand Slam. The 2010 victory was also their 12th major doubles title together and their second French Open crown.
The win had another milestone attached: Serena and Venus jointly became the world No. 1 doubles team, the first sisters to share that ranking.