Serena Williams has revealed how she feared her celebrated career was over four years and six grand slam titles ago.

Now the all-conquering world No.1 isn’t ruling out crowning her extraordinary comeback from life-threatening illness with a rare calendar-year grand slam sweep in 2015.

As she savoured a record sixth Australian Open triumph, a feat that elevated the 33-year-old above fellow American greats Martina Navratilova and Chris Evert on the all-time major leaderboard, Williams on Sunday recalled her darkest days in 2011.

Williams spent almost 12 months laid up after slashing her foot celebrating her 2010 Wimbledon triumph and then suffering a pulmonary embolism.

The deadly clot on her lungs had Williams on her “death bed”, as she put it.

“I didn’t think I’d ever be back on court. I really didn’t,” Williams said after a 6-3 7-6 (7-5) victory over Maria Sharapova earned her a record sixth Australian Open crown and 19th grand slam title.

“I was in the hospital thinking: ‘Am I going to make it out?’

“But I was super calm, I didn’t want to alarm my parents.

“Then I remember asking the doctor: Am I going to be able to play tennis again, you know, because it was my career.”

In an incredible renaissance, Williams has now won six of the past 13 majors since her harrowing ordeal – and since turning 30.

But the oldest Australian Open winner in professional tennis history believes “30 is the new 20” and, while she can envisage a life “on the beach or a boat”, the ageless champion says “right now that seems a little far away”.

“With technology and stuff, players are able to play longer and I can play as long as I want to,” Williams said.

“It just depends on how long I want to. I really don’t know. I do know I’m having fun. I love winning championships, I love holding trophies up at the end of the week and, more than anything, I love to do the work to get there.

“So when that stops, I’ll know I’ve probably had enough.

“(But) I want to keep winning. The last thing I want is for this to be it.”

Having left Navratilova and Evert in her wake, Williams now trails only Australian Margaret Smith Court’s all-time record 24 career majors and Steffi Graf’s open-era benchmark haul of 22 grand slam singles titles.

The French Open is her next target and, as reticent as she is to publicly talk up her chances, Williams refuses to dismiss the possibility of winning all four majors in 2015, a scenario that would have the US superstar level with Graf by the end of the season.

“I’ve had an opportunity five times to do a career grand slam and I’ve never done that,” said Williams, who achieved the so-called “Serena Slam” in 2002-03 by holding all four grand slam trophies simultaneously but not the same year.

“I don’t know, I’m not going to say it’s not going to happen, but I’m not putting it out there right now.

“I’m going to enjoy the moment and then hopefully I’ll win Roland Garros.”

The world No.1 plans to play a limited schedule this season, putting all energy into the majors.

“Definitely am not going to play as much this year, and I’m just going to go for everything when I do play,” she said, embracing the opportunity to try and catch Graf.

“I definitely feel I’m ready for it. I’m going for it. I’m not afraid of it.”

WOMEN’S ALL-TIME GRAND SLAM SINGLES TITLE LEADERS

24: Margaret Smith Court (AUS)

22: Steffi Graf (GER)

19: Serena Williams (USA), Helen Wills Moody (USA)

18: Chris Evert (USA), Martina Navratilova (USA)

12: Billie Jean King (USA)

9: Monica Seles (YUG/USA), Maureen Connolly Brinker (USA)

8: Suzanne Lenglen (FRA), Molla Bjurstedt Mallory (NOR/USA)

PAST 25 AUSTRALIAN OPEN WOMEN’S SINGLES CHAMPIONS

2015 – Serena Williams (USA)

2014 – Li Na (CHN)

2013 – Victoria Azarenka (BLR)

2012 – Victoria Azarenka (BLR)

2011 – Kim Clijsters (BEL)

2010 – Serena Williams (USA)

2009 – Serena Williams (USA)

2008 – Maria Sharapova (RUS)

2007 – Serena Williams (USA)

2006 – Amelie Mauresmo (FRA)

2005 – Serena Williams (USA)

2004 – Justine Henin (BEL)

2003 – Serena Williams (USA)

2002 – Jennifer Capriati (USA)

2001 – Jennifer Capriati (USA)

2000 – Lindsay Davenport (USA)

1999 – Martina Hingis (SUI)

1998 – Martina Hingis (SUI)

1997 – Martina Hingis (SUI)

1996 – Monica Seles (USA)

1995 – Mary Pierce (FRA)

1994 – Steffi Graf (GER)

1993 – Monica Seles (USA)

1992 – Monica Seles (USA)

1991 – Monica Seles (USA)

SERENA WILLIAMS’ GRAND CAREER:

* Age: 33

* Born: Saginaw, Michigan, USA

* Lives: Palm Beach Gardens, Florida, USA

* Height: 175cm

* Weight: 70kg

* Ranking: 1

* Career-high ranking: 1 (2002)

* Plays: right-handed (two-handed backhand)

* Career prize money: $US66,600,759 ($A85.85 million)

* Career titles: 65

* Career win-loss record: 691-120

* Grand slam win-loss record: 266-39

* Grand slam titles: 19 (Australian Open 2003, 2005, 2007, 2009-10, 2015; French Open 2002, 2013; Wimbledon 2002-03, 2009-10, 2012; US Open 1999, 2002, 2008, 2012-2014)

* Australian Open win-loss record: 68-9

* Best Australian Open performances: champion 2003, 2005, 2007, 2009-10, 2015

ROAD TO AUSTRALIAN OPEN TITLE:

* 1st rd: bt Alison Van Uytvanck (BEL) 6-0 6-4

* 2nd rd: bt Vera Zvonareva (RUS) 7-5 6-0

* 3rd rd: bt 26-Elina Svitolina (UKR) 4-6 6-2 6-0

* 4th rd: bt 24-Garbina Muguruza (ESP) 2-6 6-3 6-2

* QF: bt: 11-Dominika Cibulkova (SVK) 6-2 6-2

* SF: bt Madison Keys (USA) 7-6 6-2

* F: bt 2-Maria Sharapova (RUS) 6-3 7-6 (7-5)