Cape Town - Serena Williams revealed she was far from her best following her poor performance against Johanna Konta on Tuesday.
The former world number one managed to win just one service game against Konta as she went down in straight sets at the Mubadala Silicon Valley Classic.
"I'm taking everything a day at a time," the 23-time Grand Slam champion told wtatennis.com.
"I think she played better in this match than she did in about 18 months, so I think that's a good thing for her. I know I can play a zillion times better, so that kind of helps out too.
"I have so many things on my mind, I don't have time to be shocked about a loss. I clearly wasn't at my best. I can only try to be there. When I was out there, I was fighting. I wasn't just giving it away. I was moving a lot better - I'm just trying to take the positives.
"I think she played well in the second set. I think I wasn't sharp at all in the first set, and I think she got confident, and she clearly ran away with it."
Apart from this result, Williams has enjoyed a decent return to tennis since her pregnancy, reaching the last 16 at Roland Garros and the final at Wimbledon.