Even with her powerful serve and formidable physical gifts, Serena Williams is getting the most praise from fellow players for her mental toughness and confidence when facing adversity.

World No.1 Williams is trying to complete the first Grand Slam since Steffi Graf in 1988 by winning the US Open for a 22nd Slam singles crown to match Graf’s Open Era record, two shy of Australian Margaret Court’s all-time record.

“She’s just a beast,” said American Donald Young, who won Saturday to reach the fourth round.

“I think she turns it on whenever she wants to. It’s tough. It’s a lot of pressure. The way she’s handling it is like a true champion.”

Williams struggled early in her past two matches, even dropping the first set against Bethanie Mattek-Sands before rallying to win the last eight games and advance to Sunday’s fourth-round meeting with fellow American and 19th seed Madison Keys.

“Serena is inspiration for everyone who is on the tour, for sure. She’s kind of big champion,” said fifth seed Petra Kvitova.

Williams has been pushed to three sets 10 times in 24 Slam matches this year and won them all, eight of them after she dropped the first set.

Williams, who holds all four major titles, has tried to downplay the traditional Grand Slam and pump up the `Serena Slam’, a feat she has achieved twice, when winning four slams in a row.

Williams did that in 2002-03 when she won the French, Wimbledon and US Open in 2002 and then the 2003 Australian Open and again this year, winning the 2014 US Open and the first three majors this year.

But the buzz of fans, sellout crowds for her matches and talk around Arthur Ashe Stadium says more about how the tennis world regards what Williams is on the verge of achieving.

“I guess in her mind she’s trying to play it down,” said Samantha Stosur, who beat Williams in the 2011 US Open final – Serena’s most recent loss on the New York hardcourts.

“It’s amazing regardless, whether it stays the way it is or whether she gets the calendar Slam and makes it five in a row.

“Either way, everybody else has got to admire. I mean, if I was in that position, I’d probably try and play it down too and not think of it as such a huge deal and want it playing on my mind all the time.”