World number one Serena Williams battled past spirited Venus Williams in thrilling three sets to progress through to the US Open semi-finals at Flushing Meadows.
Serena claimed a 6-2, 1-6, 6-3 win over sister Venus in an enthralling quarter-final contest that lasted an hour and 38 minutes.
Although the 21-time Grand Slam champion clinched the first set with ease, Venus produced a spirited fightback in the next set to force a decider.
Eventually, Serena prevailed over her older sister as she smashed 12 aces and 35 winners to inch closer to within two victories of history.
With the win, Serena stands only two wins away from securing the first calendar Grand Slam since Steffi Graf in 1988 and will next face her Italian opponent Roberta Vinci in semis.