INDIAN WELLS, CA, USA - 23-time Grand Slam champion Serena Williams booked a clash with elder sister Venus after another tough challenge at the BNP Paribas Open, outlasting former French Open semifinalist Kiki Bertens, 7-6(5), 7-5 in just under two hours.
"I'm getting there. I have a long way to go. I have such a long way to go," she said in her post-match press conference.
"It definitely felt better than the first round, but I'm still a little rusty. I'm still making errors that I don't normally make. I call this a trial run, of traveling with the baby and all of this is just so new to me."
Williams played her first singles match in over a year on Thursday night after giving birth to daughter Alexis Olympia and marrying husband Alexis Ohanian, and continued to show off her ever-sharp competitive instincts, striking 22 winners on Stadium 1 court against the big-hitting Dutchwoman.
Bertens grabbed the first break of the opening set behind some blistering groundstrokes, but couldn't serve it out in the tenth game as Serena swept the ensuing tie-break.
"It's always good to get a tiebreak win, especially the first set under your belt. She was playing well. She played really well in that first set. She was ahead.
"That was also really good, because being able to come back and feel that rush of, 'Okay, I'm down, I'm down, but I'm still fighting.' To be able to come back I think was also really important."
The duo twice exchanged breaks in the second before the former World No.1 earned the decisive advantage at 5-5, saving a pair of break points to clinch victory after an hour and 51 minutes on court.
Up next for the American is none other than sister Venus, who advanced into the third round earlier in the day over Sorana Cirstea. Venus and Serena last played in the Australian Open final, where Serena broke Stefanie Graf's Open Era record of major titles.
"She's had such a good year last year and playing fantastic tennis. But I have to play a seed regardless, sooner than later most times for the next couple of tournaments. So I have to be ready. Whether it's Venus or anyone else, it's going to be someone.
"Obviously I wish it was anybody else in the draw, literally anybody, but that's okay. Just have to go out there and see how I am and do my best."
Monday will be the 29th match of their storied rivalry, one that dates back nearly two decades.
"I don't think I have a favorite match. I definitely don't have a favorite match. I really abhor every time we play, but I do enjoy the battle when I'm out there. It's just afterwards I don't like it as much."