Behind each backstop, along each sideline and even from the Centre Court ivy, the old club was festooned with festive purple.
The Olympics are in town, and Wimbledon has never been so colorful. Williams — a five-time Wimbledon champion and four-time Olympian — fully approves.
"As much colour as we can get for the Olympic spirit, it's great," Williams said. "I think it's what we want to see. It's still Wimbledon, but for every Olympics you have to have that Olympic feel."
Two days before the start of play, workers were still finishing preparations. But it was clear this tournament will be unlike any before at Wimbledon, a gold medallist when it comes to tradition.
From one end of the grounds to the other, the club's distinctive dark green has given way to patches of Olympic purple and lime green. The colours even adorn the building that houses the Wimbledon Lawn Tennis Museum.
On Centre Court, the Royal Box remains all dark green. However, Olympic rings hang on purple banners over every exit tunnel, while the purple media area has been expanded to stretch across three sections at the top of the stadium.
Rings even adorn the local landmark St. Mary's Church — at least that's the illusion. For those strolling on the picturesque brick walkway that descends from the grassy picnic hill, the church steeple seems to spring out from behind a purple banner draped from an overhead walkway.
Military fatigues provide another new colour scheme, thanks to the British Army's extensive presence to help with security. At the highest point on the grounds, with the London Eye visible in the distance, half a dozen British soldiers sat at shaded picnic tables smoking and sipping coffee.
Other colours are coming, because gone is Wimbledon's dress code requiring players to wear predominantly white. Maria Kirilenko of Russia took advantage by practicing in red tennies, while doubles partner Nadia Petrova wore all blue.
Williams practiced in mostly white, saving her team outfit for the first round.
"I love white on the grass, but of course I want to wear my colours for the U.S.," she said. "Red, white and blue, baby. A lot of blue, actually. You'll see it soon enough — singles and doubles."
It's all a big change for a club so unaccustomed to frills that it refers to its annual tournament simply as "The Championships." At Thursday's draw, longtime BBC-TV commentator John Barrett looked out on the grounds and soaked up the scene with a smile.
"We knew it was going to be very different, and I think it looks wonderful," Barrett said. "I rather like this purple background. It sort of links this with the other sports at the Olympics. You'll see it on the telly with the football and all.
"I don't think the Championships need to be played in this environment because they have their traditions. This is an Olympic tradition, and I think it's a very fine one."
There are other changes. Sessions may be longer, with four matches instead of the customary three on Centre Court, and the games planning to use the lights that came with the recently added retractable roof.
Crowds will be smaller, with attendance capped at 26,000 per day, compared with 40,000 or more for Wimbledon.
Food will be different, too. At the base of the picnic hill is a burger stand offering Olympian beef. Olympic treat huts have replaced concessionaires hawking strawberries and cream or ice cream.
Pimms, a Wimbledon staple, isn't on the menu. For branding reasons, the gin-based drink is being sold as "No. 1 Cup."
Inside the Wimbledon Shop — which sometimes attracts longer lines than the spectator queues for the courts — workers stock shelves with Olympic towels (20 pounds or about $31), skirts (34 pounds or about $53) and windbreakers (69 pounds or about $108).
The grass looks great — much better than at the end of Wimbledon, with worn patches reseeded in a rush job. Groundskeepers experimented for two years to help the lawn rebound quickly, and a recent spell of warm, sunny weather helped.
Perhaps the oddest new sight is the 12-foot-high shrub near an entrance, sculpted to resemble the one-eyed Olympic mascot holding a tennis racket.
Nearby, the bronze statue of 1930s champion Fred Perry seems oblivious to the games, with no logos or purple trimming evident. But then, bronze is an Olympic colour, too.