She featured in an exhibition match in Dubai and lost to Ostapenko and also played doubles with sister Venus in the Fed Cup.
"She (Cirstea) played great points".
She is not yet in prime form, not yet in prime shape, but in her first two matches she has proved she still has staying power, coming to the net effectively, something she appears to be emphasizing in this comeback, and playing the crucial points with trademark intensity. 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.
Venus in her new conference, talked about where Serena's game is right now coming back from having a baby: "She's playing really well and just honing her game". "I'm just out here on this journey doing the best I can".
Serena, who gave birth to her first child six months ago, has not played a full tournament since the 2017 Australian Open when she was in the early stages of her pregnancy with daughter Alexis.
Top-ranked Simona Halep beat Kristyna Pliskova 6-4, 6-4, and Petra Kvitova rallied past Yulia Putintseva 6-7 (4), 7-6 (3), 6-4 for her 14th consecutive match win.
"Obviously I wish it was anybody else in the draw, literally anybody, but that's okay", she said. "Whether I win or lose, there's so much more to my life".
It will be the 29th between the pair, with Serena leading the head-to-head record 17-11.
Fourth seed Elina Svitolina of Ukraine beat Germany's Mona Barthel 6-4, 6-3 while compatriot and No. 12 seed Julia Georges defeated Russia's Natalia Vikhlyantseva 6-4, 6-1.
Men's world number 1 and 20-times Slam champion Roger Federer was made to wait after taking a 6-3 lead against Argentine Federico Delbonis.
There were no such problems for fifth seed Dominic Thiem of Austria as he beat Stefanos Tsitsipas of Greece 6-2, 3-6, 6-3. The match got suspended for the day due to rain.
Wild card Danielle Collins defeated U.S. Open finalist Madison Keys 6-3, 7-6 (1) to continue a string of upsets.More news: Engine woes: Aviation watchdog grounds 11 Airbus planes of IndiGo, GoAir