* Shaky Williams recovers to beat unheralded Friedsam
* Fifth seed Wozniacki knocked out by Germany's Goerges
* Nadal, Djokovic and Murray reach third round
By Martyn Herman
PARIS, May 28 (Reuters) - The pre-tournament shortlist of favourites for the French Open women's crown continued to shrink and for a while on Thursday it looked as though top seed, Serena Williams, would also vanish.
Shortly after former world number one Caroline Wozniacki was knocked out by Julia Goerges, meaning the third, fifth and sixth seeds had all gone before round three, Williams, 33, faced unheralded 21-year-old German Anna-Lena Friedsam.
It looked like a mismatch but 105th-ranked Friedsam gave the 19-times grand slam champion a torrid time on Court Suzanne Lenglen, taking the first set before a nervy Williams recovered to scrape into the third round 5-7 6-3 6-3.
Twice former champion Williams has suffered at the French Open before -- last year when she was beaten by Spain's Garbine Muguruza at the same stage and more memorably in 2012 when France's Virginie Razzano knocked her out in round one.
With the American's groundstrokes sailing over the baseline and even her fearsome serve deserting her in the first set -- she was broken three times -- another blot on her incredible grand slam record loomed.
Even when she led 4-2 in the second set, Williams appeared shaky, going 0-40 down and dropping serve, but once she got level and broke Friedsam's serve at the start of the decider she relaxed.
"A win is a win and as long as you live to survive the next day, you can always improve," Williams said. "I know my level is literally a hundred times better than I played today.
"I take more solace in the fact I can play better as opposed to the fact that that's the best I could play -- then I would be in trouble."
She will have to sharpen up against former world number one Victoria Azarenka of Belarus in the next round.
Denmark's fifth seed Wozniacki joined the exodus of leading players, which includes Romanian third seed Simona Halep, last year's runner-up, and number six Eugenie Bouchard of Canada, by losing 6-4 7-6(4) to Goerges.
Fourth-seeded Czech Petra Kvitova survived her own trial, however, coming back to beat Spain's Silvia Soler-Espinosa 6-7(4) 6-4 6-2 despite 54 unforced errors.
In contrast to the women, the men's favourites have been largely untroubled and that continued as holder Rafa Nadal, top seed Novak Djokovic and Andy Murray reached the third round.
All eyes have been on Nadal as the Spaniard battles to rediscover his mojo and claim a record-extending 10th French Open title, but there were few weaknesses on show as he beat compatriot Nicolas Almagro with relative ease.
Nadal took his stunning Roland Garros record to 68-1 with a routine 6-4 6-3 6-1 victory -- his fourth without dropping a set against Almagro on the Paris clay.
Djokovic needed an injury timeout when he slipped in a straight-sets win over Luxembourg's Gilles Muller, although he looked untroubled when shaking hands with watching Swedish soccer great Zlatan Ibrahimovic.
"I made a couple of slides that were quite unusual and it happened in those dynamic movements, I jammed the hip a little bit. Thankfully it's nothing serious," said the Serb who faces Australian upstart Thanasi Kokkinakis next.
Third seed Murray was given a fight by Portugal's Joao Sousa but came through 6-2 4-6 6-4 6-1 to set up an eye-catching clash with Australia's trailblazer Nick Kyrgios.
Some of the biggest cheers came elsewhere in the grounds.
On Court One, nicknamed the Bull Ring, former women's champions Francesca Schiavone and Svetlana Kuznetsova battled for three hours and 50 minutes before Italian Schiavone prevailed 6-7(11) 7-5 10-8 having saved a match point.
Kokkinakis beat his country's former great hope Bernard Tomic in another cliffhanger, saving three match points at 5-2 down in the fifth which he won 8-6, while fellow teenager, 18-year-old Borna Coric of Croatia, edged Spanish 18th seed Tommy Robredo, also in five sets.
Coric will face Jack Sock in round three, one of only two surviving Americans in the men's draw after John Isner lost to Frenchman Jeremy Chardy. (Editing by Ed Osmond and Ken Ferris)