A point from defeat twice over the course of more than two hours on court, Ajla Tomljanovic had the most dramatic victory of Tuesday's day session at the Mubadala Silicon Valley Classic. 

Trailing 6-1, 5-3 against Amanda Anisimova, the Aussie won five straight games - saving a match point in the 10th game as the American served for a spot in the second round - and later came from a break down twice in the decider to seal a 1-6, 7-5, 7-5 comeback victory in 2 hours and 10 minutes.

Tomljanovic won four straight games to win the match as well, and erased Anisimova's second match point to hold serve in the ninth game. In all, the World No.50 withstood 40 winners from the American's racquet, thanks in part to the fact that Anisimova also racked up 40 unforced errors. 

"She really kind of killed me in the first set. I wasn't ready to get so many tough balls, even after some good serves I hit. I just knew I had to stay really close to her in the second set," Tomljanovic said in her on-court interview.

"I was fortunate to come back from a few match points down, but I thought she played some really great tennis at times. I'm happy to be through.

"I stayed mentally tough. I didn't give up even though I was down 6-1, 5-3 pretty comfortably, and I definitely found ways to win today. Even though I didn't feel great in the first set, I knew my tennis was there if I just kept hitting out and finding my spots, which I did."

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Also advancing in the day session were No.8 seed Yulia Putintseva and former Top 10 player Kristina Mladenovic, straight-sets winners over Donna Vekic and Han Na-lae, respectively, and wildcard Claire Liu, who beat Dayana Yastremska in three sets, 6-3, 4-6, 6-4.

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In the first of two all-American matches in the night session, Sloane Stephens beat Catherine McNally, 6-4, 6-2, after trailing 4-0 in the opener. The victory was Stephens' first match in one day over a month, with her last match being a third round defeat to Liudmila Samsonova at Wimbledon on July 2.

"I was feeling a bit of nerves. I was unsure of the sun and I was like a little bit shaky, so when I came out here, I knew it was going to be tough but I just had to calm down and play," Stephens, who won eight straight games in the middle of the match, said.

"I think when I was down 4-0 I realized, 'Okay, now it's time to play.' It was a tough start but I was happy to reel off some games and get that set, and then eventually, the match.

"I haven't played here in nine years. I have family here and I have so many fans here that I haven't been able to see... so I was happy to get the win."

She'll next face No.7 seed Danielle Collins, who closed out the night with a 6-4, 6-3 win over Shelby Rogers for her sixth straight win. The Palermo champion saved three break points at 4-4 in the opener en route to winning five straight games, but hit back to win the last three after Rogers leveled at 3-3.

Collins hit 22 winners to 18 unforced errors, nine of which were double faults, and went a perfect 4-for-4 on break point opportunities against Rogers' serve. Conversely, she saved 5 of the 7 chances Rogers had to break her. 

"Towards the end, I was thinking that if this had gone any longer, I would've needed a coffee. I was getting a little grumpy," Collins joked after the match. "I was scaring myself with some of my shots sometimes. I was missing some by a lot, making some good shots, so I wasn't giving myself or my opponent much rhythm. It was a sporadic performance, and being the perfectionist that I am, I was driving myself crazy.

"I was happy to pull out the win, especially against Shelby. She's such a fierce competitor and she's always bringing her best shots and never gives up. I just had to keep bringing it back and doing everything I could to pull out the win."

Collins and Stephens have never played previously.