Serena crushed out of the US Open semi-finals last year against Roberta Vinci, which ended the 34-year-old's hops of sweeping all four Majors of the calendar. She had not win a title since then until last weekend when she beat compatriot Madison Keys to lift the trophy in Rome, reports Xinhua.
Despite the low profile, the 21-time Grand Slam winner, who has played only four tournament in 2016, entered three finals, including that of the Australian Open where she lost to Germany's Angelique Kerber, the third seed here for this year's French Open.
"For me, if I'm not winning, I'm not happy about my year," said Williams on Friday. "Four tournaments, three finals isn't bad for, I think, everyone else. Then again, I'm not everyone else.
"I guess when you win all the time, if you go to a couple of tournaments and don't win them, it's like you're in a drought."
Serena pulled out of Madrid through illness but did not drop a set in Rome, the only clay tourney she attended before coming to Roland Garros.
"It felt good to win in Rome, obviously. I was feeling pretty confident going into some of those matches. Especially the last few I felt a lot better.
"Even if I'd have lost, I feel like some of those matches really gave me the match play that I needed," she added.
The 2016 French Open gets underway on Sunday. The women' s singles final is set for June 4, one day ahead of the men's final.