Williams wore her "business bun" as she put away her opponents in singles and doubles. (AP)

Serena Williams' dominant day on Centre Court wasn't always so.

She dropped her second singles set, 6-4, to Alison Riske on Tuesday, and, when Riske bopped a backhand winner down the line for 3-3 in the third, their quarterfinal match could have gone either way.

But then, seconds later, Williams put her hair up in a loose bun, and longtime fans of hers immediately knew something was up.

Serena subsequently reeled off six consecutive points—including a a put-away swinging volley, an ace up the T and a blasted backhand winner of her own—and won the remaining three games to snatch the match away from Riske in the span of 15 minutes. 

It'd be silly to say the hairstyle change made the difference, but it certainly didn't hurt.

Williams later explained that the decision was primarily due to the wind, and that it was more practical than symbolic. "I just needed to get it out of the way," she said. "Put the business bun up and just get to business."

She'll be considered a top contender in her remaining singles business, facing Barbora Strycova in the semifinals, with Simona Halep and Elina Svitolina fighting for the other spot in the final. 

The business bun stayed in for Serena's mixed-doubles match alongside Andy Murray later in the day, and her command of the court didn't drop off at all—just look at how she handled Fabrice Martin's 138-mph serve in the first set: 

And she later outdid Rafael Nadal with this unreturnable angled return, en route to their 7-5, 6-3 win over Martin and Raquel Atawo. 

The Murray-Williams team plays again on Wednesday, against top seeds Bruno Soares and Nicole Melichar. It'll just be doubles on Serena's singles day off, but considering how she's treated the tournament up to this point, she'll also be all business.