The first set was a tense contest with the athletes trading early breaks until Williams broke to lead 5-3 and then defended two break points to win the opening set 6-3.
Halfway through the second set, Williams ran towards the net for a volley and twisted her right ankle but was still able to break Martic’s serve to lead 3-2, she immediately requested for treatment from the tournament trainer to address the problem.
The 37-year-old American, attempting her 24th career Grand Slam medal to equal Margaret Court’s all-time record, routed Croatian 22nd seed Petra Martic 6-3, 6-4 to enter the last eight for the 16th time in one hour and 32 minutes.
Talking about the injury, Williams said: “I feel fine right now physically, That was a little frustrating but I wanted to get it compressed really fast so that’s what I did [with the medical timeout]. She advances to a meeting with Chinese 18th seed Wang Qiang.
“I just wanted to get, as I said, get some compression on it and tape it even stronger and that way I can at least try to finish the match, It affected me a little in mind because I’ve had a rough year with injuries and I thought ‘Oh my god, not again! I’m finally walking’ but thanks to you guys [addressing the crowd I got through it.”
“But I’ll see tomorrow. So far I’m good. I have been managing it. We’ll see tomorrow.”
The 23 time Grand Slam titleholder path to a 10th US Open final opened up with the dismissal of the top two seeds on her side of the draw, with Wang eliminating the French Open defending champion Ashleigh Barty and 2016 runner-up Karolina Pliskova also failed.
Williams, who has also fought knee and back injuries this summer, insisted an apparently easier path to the trophy won’t change her strategy in New York.
She said: “I can’t afford to look at it that way. Every single match I have played, people come and they played their best. The women that I play are not generally playing at this level against other players in the locker room, so for me, I have to be the greatest whether it’s against the second seed, the number one seed, or the 80th player in the world.”
“I have to show up or else I’m going to go home.”
Watch the full match highlight below:
Williams acquired her first Grand Slam title 20 years ago at the US Open at age 17, however, the eighth seed still feels she has lots in the tank as she seeks her first major since the 2017 Australian Open.
“I always said I would wake up one day and say, ‘I’m done.’ That day hasn’t come yet for me,” Williams said.
“I’m still playing pretty good tennis. I do look at Roger (Federer), like today, and the guy is incredible.
“His game is shockingly amazing. So there is no reason that he shouldn’t be out there with his ability, and I feel the same way about mine.”
Williams also affected upon the passionate displays following Saturday’s third round showdown between the current champion Naomi Osaka and 15-year-old Coco Gauff, in a match she booked as “the future of women’s tennis“.
Osaka defeated Williams in a rough 2018 final governed by a provocative game penalty inflicted by chair umpire Carlos Ramos against the US star, comforted Gauff after striking a huge defeat on the teen genius.
“I thought it was so sweet and so amazing,” said Williams, who stepped in to try and calm the situation after stadium boos during last year’s trophy ceremony soured Osaka’s shining moment.
“Generally I try to be really sweet after the match. I mean, last year obviously I was comforting Osaka, she was comforting me.
“There has been many a time I have been extremely outgoing towards my opponent because at the end of the day we’re all human and we see each other sometimes more than I see my family.”
Williams challenges China’s Wang Qiang next, after the 18th seed beat world number two Ashleigh Barty in the last 16.
She will move level with Margaret Court on the most Open-era Grand Slam titles if she prevails at Flushing Meadows.