Serena Williams continues her run at the BNP Paribas Open in Indian Wells, edging 26 year-old Dutch Kiki Bertens in two sets,7-6(5), 7-5 , to book a date with her sister Venus Williams, in the third round.
It was a blistering encounter between the 23-time Grand Slam champion and Bertens who was a former French Open semi-finalist.
Serena who said she was still trying to reach her form outlasted her in just under two hours.
Venus in an earlier match had beaten Romania Sorana Cirstea 6-3 6-4.
The match on Monday will be the first time the two sisters will clash on court, since the final of the Australian Open last year, which Serena won, even though she was already pregnant.
She had her baby in September and had skipped defending her Australian title, because she felt she was not ready yet to play. She featured in an exhibition match in Dubai and lost to Ostapenko and also played doubles with sister, Venus in the Fed Cup. She lost the match.