Serena Williams has made a wise move by asking Rennae Stubbs to help her prepare for a farewell US Open appearance, Chris Evert said on Friday.

Ahead of her 21st singles appearance at Flushing Meadows, Williams has brought in former doubles world number one Stubbs, and has been working closely on court with the Australian.

Stubbs has experience of coaching the likes of Karolina Pliskova, Eugenie Bouchard and Samantha Stosur, and the 51-year-old won six grand slam doubles titles, so knows all about performing on the big stage.

Her fresh input could prove invaluable, Evert believes, with Williams no longer having her long-time coach Patrick Mouratoglou in her corner. He now coaches Simona Halep.

Ahead of Williams' last event before retirement, Evert told ESPN: "I know she's been practising hard for this tournament.

"She has Rennae Stubbs helping her which is a positive thing. Rennae encouraged her to play matches against other women to get a taste of how other women play, because before she was just playing with her coach and not really moving a lot in practice, just hitting a lot of balls that were coming right to her.

"What I think she needs to work on more is playing the other women, knowing their game, moving corner to corner and getting that moving going. That's the only thing that's really preventing her from getting that A or B game at this point."

Williams begins her campaign on Monday against Danka Kovinic of Montenegro, the world number 80 who beat reigning US Open champion Emma Raducanu at this year's Australian Open.

Evert is the only woman in the Open Era (since 1968) to have reached more grand slam singles finals than Williams, one ahead of her fellow American after embarking on 34 runs to title matches.

However, Evert lost 16 of her finals, whereas Williams has been beaten only 10 times in 33 such matches.

The 40-year-old Williams therefore has 23 grand slam singles titles, putting her one short of the all-time record held by Margaret Court, but top of the Open Era list.

Evert does not believe Williams will be turning up purely to say goodbye.

"This is a big tournament for Serena Williams and this is an opportunity for people to really get one last look at her, and that's why everyone's trying to buy a ticket for Monday, Tuesday, Wednesday night," Evert said.

"She's transcended tennis, she's revolutionised tennis with her power game. But also off the court, her fearlessness and ability to just say whatever she wanted to say, not caring what people thought, her honesty, where she came from and how she's dealt with that.

"I feel she has so many different platforms where she's helped women: women who work who have children, women of colour. I can't say enough about the influence she's had on people."

It remains to be seen whether Venus Williams will follow Serena into retirement after the upcoming slam in New York, but few would be surprised.

At the age of 42, seven-time grand slam singles winner Venus would also deserve a rapturous send-off.

"Venus gets overshadowed by little sis," said Evert. "But Venus on her own has established, accomplished so much, won so many grand slams, singles and doubles, and handled this whole sister thing with grace."