Defending champion Venus Williams, chasing a fifth Wimbledon title, had to withstand an early onslaught from Anne Keothavong before moving smoothly into third round of her favourite tournament.

Keothavong, the British No1, created chances to take the first set off one of the greatest women's grass court players the game has seen but eventually fell 7-5, 6-2 in a match lasting one hour 44 minutes.

Keothavonghas broken into the world's top 100 to prove that British women's tennis is no longer a joke.

She was the first British woman for nine years to earn the right to enter the first round without the need to qualify or receive a wildcard and has the game to make that a regular occurrence.

Although Keothavong, at a career-high ranking of 92, won only one point in the first two games the girl from Hackney soon came to terms with the occasion and eventually found her range.

She was helped by the American's inconsistency, particularly the forehand which ended up in the net with alarming regularity for the No7 seed.

So it was a surprise when the titleholder conjured up the first break of serve of the match to lead 2-0. It was a huge moment for Keothavong and a lesser player would have wilted.

However, she recognised the flaws in Williams's game and kept battling in the rallies, getting the break back when her opponent fired a backhand down the line wide - much to the delight of the Centre Court crowd who were warming to the home girl.

They were even more impressed when Keothavong saved four break points in the next game, which featured a Williams overhead smashed with enormous power in the bottom of the net. The error drew gasps from fans not used to witnessing park court errors from a Grand Slam champion.

The British No1 should have then capitalised on her good fortune, creating a staggering eight break points on the Williams serve, only for the American to avoid falling behind.

With Williams still unable to find her range with that forehand - she produced 20 unforced errors in the set - Keothavong had another service break opportunity in the seventh game after her opponent slipped going wide and it was to be her last chance to save the set.

Williams showed her greater big match experience by turning up the pressure after taking a 6-5 lead and Keothavong made an horrendous error just moments after winning the best point of the contest.

She put away a cleverly weighted cross court winner at the net and then prepared to serve with the crowd still murmurings its admiration.

Unfortunately, Keothavong's ball toss was affected by the wind and she ended up only connecting with the rim of her racket and the ball bobbled towards the bottom of the net.

She was only able to deliver a weak second serve and after 68 minutes, Williams had finally established herself as the favourite with a 7-5 first-set success.

It was a deflating moment for Keothavong, whose serve had reached 109mph - 10mph slower than the her opponent's but good enough to bring her enough cheap points to keep the match a real contest.

However, her groundstrokes lacked the consistency of depth to really trouble the American, who has amassed nearly £15million in prize money compared to the Briton's haul of £200,000.

Now that Keothavong has earned the right to gain entry to the major tournaments thanks to her improved ranking, there will be other days like this and having faced the reigning champion on Wimbledon's centre court and not been embarrassed, her self confidence will have been boosted.

There was, however, a flat end to the match, and British interest in the women's singles, with Keothavong's third double-fault bringing the contest to a close.

Williams now faces world No101 Maria Jose Martinez-Sanchez, who caused a shock by beating No32 seed Sania Mirza 6-0, 4-6, 9-7.

Mirza, who had a wrist surgery in April, had been expected to defeat Martinez Sanchez as the Spaniard had never won a match at the grasscourt Grand Slam until this week.