Serena not ready for final curtain

Serena Williams is closing in on her 35th birthday and has just experienced back-to-back Grand Slam final losses for the first time.

But the American superstar and world No 1 is not ready to be dethroned any time soon.

Williams' latest attempt to equal Steffi Graf's Open era record of 22Grand Slam titles was thwarted on Saturday by Spain's Garbine Muguruza in the French Open final.

Back in January, Angelique Kerber pulled off a similar shock to snatch Williams' Australian Open title while in New York last September, Serena's hopes of a calendar Grand Slam were upended by Italian trialhorse Roberta Vinci in the semifinals.

So Williams' Grand Slam haul has stalled at 21, but she is still the favorite to win a seventh Wimbledon when the third major of the year opens in three weeks.

"The only thing I can do is just keep trying," said Williams, who was attempting to win a fourth French Open after 2002, 2013 and 2015.

"In Australia, Ann Kerber made 16 errors in three sets, you know, so what do you do in that situation? Today Garbine played unbelievably.

"It's definitely something I want to dissect and see what I can learn from and what can I do to get better."

Williams has been down and out before and bounced back in style.

In 2011, she underwent two foot surgeries and fought life-threatening blood clots on her lungs.

Her absence from the tour saw her world ranking slip to No 103.

In 2014, she lost in the fourth round at the Australian Open, in the second round at the French Open and in the third round at Wimbledon, but hit back with the US Open.

In between, she won 11 WTA titles in 2013 and put together a 34-match win streak between Miami and Wimbledon.

Last year, when she collected a sixth Wimbledon, it allowed her to celebrate a second "Serena Slam" of all four majors at the same time.

She had already achieved a first Slam sweep in 2002.

Despite her record and status as one of the greatest players of all time, there were obvious problems in a damp and chilly Paris, hinting that Williams' renowned power is possibly starting to diminish.

She finished top of the heap for aces served with 36 and tied for the fastest serve of the event at 196km/h in Saturday's final.

But she also had one of the lowest first serve percentage rates at 60% and managed to convert only 30 of 73 break points over the two weeks.

Her team and even her rivals insist that the American, despite being in her third decade on tour, is not finished as a dominant force in the game.

Her French coach Patrick Mouratoglou has no doubts that she will reach the magical figure of 22.

"Serena was far from her best level today," Mouratoglou told eurosport.fr.

He has masterminded eight Slam titles in Williams' last 16 tournaments, compared to 13 from 47 before they hooked up after a first round loss at the 2012 French Open.

"It will take as long as it takes, but Serena will win a 22nd Grand Slam," he added.

"It's not easy to break records, it wasn't easy for her to get to 18 (the number won by Chris Evert and Martina Navratilova)."

Muguruza's coach, Sam Sumyk, also refused to write off the American.

"It's not the end. Serena will be around for a long time��and we need her," he said.

Garbine Muguruza of Spain hugs the trophy after defeating Serena Williams for the French Open championship on Saturday. Corinne Duvreuil / Reuters