Serena Williams has suffered a foot injury scare on the eve of her US Open quarter-final as she played doubles with sister Venus.

World No.1 and five-time singles champion Williams took an injury timeout to have her right foot and ankle heavily strapped early in the second set of the sisters’ quarter-final against Russian pair, Ekaterina Makarova and Elena Vesnina.

Although the 32-year-old did not appear to be in significant discomfort, the American stars still lost 7-6 (7/5) 6-4 to the Russian fourth seeds.

Williams is due to face Italy’s Flavia Pennetta in Wednesday’s semi-finals.