Serena Williams didn't let her troublesome knee trouble her too much at the Miami Open on Saturday, as she blitzed her way into the 3rd round at the event for the loss of just four games against Romania's unseeded Monica Niculescu. Her older sister Venus was a round further on and also came through victorious, edging a close contest in two sets with the experienced Sam Stosur of Australia. There was no such joy for Britain's Heather Watson though as she was outlasted by the German Angelique Kerber, with the number 13 seed narrowly winning in three sets.

A major casualty of the second round was Canada's Eugenie Bouchard, as the number 5 seed surprisingly excited in straight sets to Germany's Tatjana Maria.

Serena had to pull out of her previous event in Indian Wells at the semi-final stage, due to her knee issues, but seemed determined to compete this week if at all possible. Her decision seemed to bear fruit in her first match in Miami, after receiving a bye through the first round. She had far too much weaponry against Niculescu, as the Romanian could not repeat her solid performance (albeit in defeat) at Indian Wells, where the two players also faced each other. This time around, the 33-year-old American strolled through the match 6-3 6-1.

She now faces Catherine Bellis in round three.

Big sis Venus faced an altogether more challenging match-up with the former US Open winner, Stosur. Both sets were tight, but both went Venus' way as she continued her recent resurgence with a pleasing 6-4 7-6 triumph. She will have to battle even harder in round four one expects, as she will meet the number four seed and close friend of Serena's, Caroline Wozniacki.

Watson had been impressive in coming through her first round match with Evgeniya Rodina, having to battle hard before claiming a three-set success. While many in England at least were turning their attentions to the national football team's Euro qualifier on Friday, Watson started her second-round tie with Kerber and trailed by one set when the weather intervened.

That rain interruption pushed the match into a second day and, despite taking the second set on Saturday and recovering brilliantly in the decider from 5-1 down, Watson crucially lost her serve when 5-4 behind. It gave the German a 7-5 3-6 6-4 victory, but she must have been impressed with the Guersey-woman's tenacity during the match.