Serena Williams won her 21st Grand Slam title with a hard-fought 6-4 6-4 victory over valiant Spaniard Garbine Muguruza in the Wimbledon final this afternoon.

The 33-year-old American has won the last four Grand Slams, dating back to last year's US Open, and if she defends her title at Flushing Meadows later this summer she will become the fourth woman to complete the calendar Grand Slam.

The last woman to achieve the feat was Steffi Graf in 1988.

Victory today on Centre Court might appear straightforward on paper, but it was far from it for the top seed. She had to overcome a shaky start against Muguruza, who had never been further than a quarter-final in a Slam before.

The 21-year-old had four break points in the first game of the match and was able to convert on the last of those before safely consolidating the advantage to move 2-0 up.

Muguruza had to save two break-back points in the sixth game to go 4-2 in front, but she couldn't move within a game of the set two games later as Williams struck to level the opener at 4-4.

Williams finished the first set on a run of four straight games as Muguruza gave her one set-point chance and it was taken by the top seed.

Muguruza was back on the board with a love hold to level the second set at 1-1, but she then lost four games in a row as Williams raced to a 5-1 lead with a streak that included a run of 12 points in a row.

Williams, who had not won at the All England Club for three years, was within a game of the match, but Muguruza fought back spectacularly by breaking twice to get back on serve.

The 20th seed saved a match point on Williams's serve, but the contest ended in anti-climactic fashion as Muguruza lost her serve to love to hand Williams victory.

On the final point, Muguruza hit wide, but the crowd didn't realise and there was a moment of confusion before Williams was confirmed as Wimbledon champion for a sixth time.