Few people can appreciate the joy and the dread stirred up by Venus and Serena Williams’s victories on Monday night at the US Open better than Venus’s boyfriend, Hank Kuehne.

Kuehne, a golfer, grew up with an older brother, Trip, who was also accomplished in their sport. Thank goodness, Kuehne said, he never had to face his brother in a match. That would have been the nearest thing he could imagine to what was up next for Venus and Serena — a showdown on Wednesday in the quarter finals of a tournament — they both desperately want to win.

“I think, it’s a very difficult dynamic,” Hank Kuehne, a PGA touring pro, said after watching Venus’s match. “My brother and I are so ultra-competitive, we play cards with each other and it turns into a bloodbath.” He added: “The thing is, Venus and Serena have done this their entire lives. It’s not fun for anyone involved, but they’re professionals.”

The Williamses have played each other 16 times, including three times at the Open — in the final in 2001 and 2002 and in the Round of 16 in 2005. Venus prevailed in 2001, Serena prevented her from defending her title in 2002, and Venus won in 2005. They met in the final at Wimbledon in July in a sublime piece of theatre that culminated with Venus’s winning her fifth Wimbledon title. Everybody wanted to see the sisters meet, but not like this.It is a situation tailor-made for disappointment.

Six years ago, when the Williams sisters squared off under the lights at Arthur Ashe, the WTA Tour was essentially the Williams Tennis Alliance. It was the fourth Grand Slam final in the previous five to feature them.

As had been the case at the French Open and Wimbledon earlier that year, Serena prevailed over her sister, securing her second Open title with a 6-4, 6-3 victory. It seems unfathomable that neither sister has been back to the final since.

Venus sat out the Open in 2003 and 2006 because of injuries, and Serena has not advanced past the quarter finals in four subsequent appearances.

“Obviously, we were playing very well then,” said Venus, who, like everyone else, expected the sister showdowns in Open finals to become a late-summer rite, like barbecues and back-to-school shopping.

In 1998, when Kuehne won the US Amateur, Trip was his caddie, not his competition. He will watch Wednesday’s match, as he did the Wimbledon final, with a mix of joy and dread. “It’s a difficult situation,” he said. “We’ll feel elated on one end, heartbroken on the other.”

In a post match interview, Serena said the draw stunk, except the word she used was more profane. NYTNs