With two more spots in the women’s semifinals hanging in the balance, the Americans were well represented on Wednesday. Three out of the four players in action were from the United States, ensuring that at least one would advance to the semifinals.

Keys overcomes injury, dispatches Venus

In the first match, two powerful hitters squared off in Madison Keys and Venus Williams. And despite being less than 100 percent physically, Keys advanced 6-3 4-6 6-4.

In the first set, if there were any nerves by the 19-year-old, she kept them hidden inside as she imposed her will on the veteran American, who could not handle her power. Keys dictated play with huge groundstrokes, placing Williams consistently on the defensive. Playing with an exuberant confidence, Keys broke the 34-year-old’s serve twice, while Williams could only strike four winners in the set.

However, just as it appeared Keys might roll to an early advantage in the second set, she quickly fell behind, dropping her serve twice. And at 1-4, the young American left the court, seeking medical attention on her leg. Upon her return, she quickly regained both of her service breaks back as Williams looked out of sorts. However, despite her difficulties, Williams would find another key service break and served out the set to even the match.

In the third set, Williams gained an early advantage as Keys favored her leg. Now playing with a taped hamstring, Keys appeared to have difficulties when stepping into some of her shots. Nonetheless, she fought back and looked to hit bigger shots, thus shortening the points. And as the set advanced, Keys found control once more. She broke Williams’ serve at a crucial time in the set and closed out the match, advancing to her first Grand Slam semifinal.

Keys, who had her hamstring taped during the injury timeout, compared Wednesday’s injury to that which forced her out of Wimbledon last season. “It wasn't as bad as Wimbledon but it was that nightmare of 'I don't want this to happen again,' so it was a little overwhelming,” she said.

Serena in peak form, rolls past Cibulkova

In the second women’s match, top-seeded Serena Williams faced Dominka Cibulkova, who reached the final at Melbourne last season. Despite struggles earlier in the tournament, Williams was in top form and advanced easily, 6-2 6-2.

Williams came out much sharper than in her previous matches, where she had looked sluggish at times. She gained an early break advantage in the first set behind a dominant display of ground strokes. The American, far more engaged in this match, piled on the Slovakian with big, powerful shots and quickly took a stranglehold on the first set. Williams easily performed at her highest level of the fortnight,thus far. She cruised to the first set in just 28 minutes.

Continuing her momentum into the second set, Williams broke service early and thwarted early attempts by Cibulkova to battle back. Williams’ game was too strong as she continued to roll through the set, making easy work of her opponent. It was an impressive performance by the American, who sent a reminder in this match that she is a strong threat to win the first major of the year.

After the match, Williams reflected, “I just knew I had to be good today, I'm just happy to be able to come through.”