NEW YORK — Even before Serena Williams set foot in Arthur Ashe Stadium on Monday night, her path through the U.S. Open to complete a true Grand Slam became a lot easier thanks to losses by other top women.

And when it was the No. 1-seeded American’s turn to play her first-round match, she was not tested one bit by a woman who appeared overwhelmed by the opponent, the occasion and, to make matters worse, an injured left foot.

So Williams moved a step closer to tennis’ first calendar-year Grand Slam since 1988 without much of a workout, reaching the second round when 86th-ranked Vitalia Diatchenko of Russia stopped playing while behind 6-0, 2-0. Williams was out there for only 27 minutes and took 32 of the 37 points that were played.

“It was definitely different and bizarre,” Williams said. “But at the same time, I was still focused. I kept thinking: Just stay focused; don’t lose it. You never know what can happen.”

The 33-year-old American told the crowd she appreciates the support she is receiving “on this journey and this milestone that I’m trying to take one match at a time.”

Diatchenko, who wore a walking boot to her news conference, said she hurt herself running sprints before the match and that she felt “sharp pain” chasing a backhand during a point. When she was drawn to face Williams, Diatchenko was happy to finally get a chance to meet a player she grew up admiring, but the experience turned out to be “terrible.”

“So painful, every step,” Diatchenko said .

Next up for Williams is Kiki Bertens of the Netherlands, who is ranked 110th, only once made it as far as the fourth round at a major, and picked up just the second U.S. Open match victory of her career by eliminating Mirjana Lucic- Baroni 3-6, 6-4, 6-2 Monday. Bertens and Williams have never played each other.

Williams is 22-0 in Grand Slam matches in 2015, with championships at the Australian Open in January, the French Open in June, and Wimbledon in July. If she adds the title at Flushing Meadows, she would be the first player since Steffi Graf 27 years ago to win all four Grand Slam tournaments in a season.

Williams also can equal Graf ’s professional era record of 22 Grand Slam singles titles – Margaret Court is the all-time leader with 24 – and can become the first woman since Chris Evert in the 1970s to win four consecutive U.S. Opens.