There were tricky moments at the end, as she watched a 62 50 lead become 62 53, even missing out on triple match point at 62 52 - but the No.1-seeded Williams never looked like she was in trouble, eventually serving out a 62 63 victory, firing a pair of aces on the last two points of the match.
The night before, Williams was named Best Female Athlete at the ESPYs across the water in Los Angeles, her second time winning the award (read more about it here). How did she feel about it?
"To be on top was really an honor for me," Williams said. "I've worked really hard, and there have been so many fabulous female athletes in the last year, so to get that award really means a lot to me."
But back to Bastad - Williams is now one step closer to another WTA title, and with her win over Tatishvili, she's 25-0 on clay this year. What are the World No.1's goals in the Swedish paradise?
"I've had a lot of time here but I've actually been spending a lot of time in the room, just staying focused on the event," Williams said. "My main goal is to do well here. I love this city, but I really love the fans, and I feel like I want to do the best that I can here. I'm staying really focused, Grand Slam style.
"You never want to go to a tournament and not win, or at least not perform your best. I don't know if I'll end up winning the tournament this week, but I want to play some of my best tennis here."
The No.2 seed, Simona Halep, wasn't so lucky, falling to Flavia Pennetta, 46 75 20 retired. Halep had won 17 of her last 18 matches but it seemed to have caught up with her this time, as after a pair of tight sets the Romanian No.1 had to stop play early in the third set because of a low back injury.
"It was a little bit of a strange match," Pennetta said afterwards. "We fought a lot in the first set. In the second set I started to play much better, much more aggressive, and I was up 5-2. I got a little bit tight and she came back to 5-all, but I was just trying to fight until the last ball, and I won the set.
"Then in the beginning of the third set I saw she was a little bit tired and injured, which is normal when you've played so many matches. I wish her the best to recover and come back very soon."
Pennetta is still working her way back up the rankings after a six month wrist injury lay-off that spanned last August to this February. How did she approach a match against such an in-form player?
"I knew going in that she's playing better than me right now, but when I go on the court I just try to play my best and always think I can win," the former World No.10 said. "It's just really important to go onto the court and believe you can win against anybody. If you don't believe, it's that much tougher."
"It feels very good, not just because it's my first WTA quarterfinal, but before the match I knew if I won I would be in the qualifying of the US Open," Hogenkamp said. "So of course it's just a great feeling. It was a really big stadium and I was really nervous but I'm glad I ended the match as the winner."
The last match of the day saw Mathilde Johansson beat Venezuelan qualifier Andrea Gámiz, 75 62.