Rock-and-Roll Tennis at US Open

THIS feels more like Fenway Park or Shea Stadium. Or is it Lambeau Field in Green Bay? Nope. It's the packed-to-capacity grandstand court at Flushing Meadow, site of the United States Open tennis championship.

And it's not a top-billed Andre Agassi or Monica Seles match, either. It's the long-haired, doubles-playing Jensen brothers from Ludington, Mich.

Fans chant and clap: ''Let's go, Jensens!'' The marquee flashes: ''JENSENS ROCK'' and ''ROCK AND ROLL TENNIS.''

Luke and Murphy Jensen say they are bringing the game of tennis to the fans. They refer to these high-profile matches as ''the show.''

Showmanship isn't new to tennis. First there was the Billie Jean King-Bobby Riggs match in 1973. A pioneering effort at crowd-pleasing, the ''Battle of the Sexes'' drew 50 million viewers on prime-time television. The 1970s and '80s brought the entertaining play of Jimmy Connors and Ilie Nastase. But the Jensens have gone over the top of the net, so to speak.

They both have long hair - Luke's is dark and tied in a ponytail; Murphy's is blonde and curly and hangs loose. They wear streamlined sunglasses for daytime matches. On this perfect, end-of-summer evening, they wear football jerseys and white tennis shorts. Luke is wearing a bandanna with Adidas stripes and Murphy a matching hat - backwards, of course.

It's high-energy tennis. After each point they score, they smack high-fives, bang knuckles, or bump chests. ''Dual hand Luke'' can serve with either hand - the only player on the tour who can.

The fans applaud each play and scream their approval or disapproval. It's not everyone's idea of the respected game. And some opponents are irritated by the Jensens' antics. (They've been called the Barnum & Bailey of tennis.) But the cheers drown out the criticism. They attract many young fans when they play.

The Jensens joined the pro circuit (ATP Tour) in 1993, winning the French Open doubles that year. They made the fourth round here, losing to Byron Black and Jonathan Stark on Monday.

Luke also plays mixed doubles with Mary Pierce. They advanced to the semifinals before losing to Meredith McGrath and Matt Lucena, 7-5, 7-6 (7-2). Pierce, who lost in the third round of women's singles, says she is having more fun playing mixed doubles than she's ever had playing tennis. Even her coach, noted guru Nick Bollettieri, said it was good to see Pierce relaxing and having fun in her mixed-doubles matches.

THE Jensens return to the court after a changeover. A fan screams ''We love you, Jensens!'' Murphy blows a kiss to the crowd. The brothers are soon up, 40-love. Luke is about to serve for the game. A fan screams, ''I love you, Luke!'' Luke stops his windup, turns around, puts his finger to his lips, and says ''Sssssshhhhhh!'' The crowd roars. The Jensens win the game.

Another changeover: Murphy towels off, then stands and waves his towel. Taking his cue, the grandstand crowd breaks into ''the wave.'' Yes, the wave at a tennis match. It sweeps around the stadium three times, and each time it nears them, Luke and Murphy stand up in front of the potted caladiums, waving their towels with the fans.

The ''BRUISE BROTHERS,'' as the marquee flashes, seem to thrive on the energy of their fans.

''It's really easy to go out and play in front of the crowd,'' Luke says after winning their match against Paul Kilderry and Kent Kinnear, 6-2, 6-7, (6- 2). His hair hangs loose now, but he's just as animated off the court as he is on it. ''There's so much electricity. You hit out on your shots, and you don't really get tight. You don't really think it's such a big, big event. And it is - it's bigger than life.''

After the match, Luke and Murphy spend 45 minutes signing their baseball-style cards for fans. On the back are quotes from the brothers. Luke on doubles, for example: ''Play it loud, play it fast, and play it hard. Doubles is a contact sport.'' Murphy on tradition: ''The only sacred tradition in tennis is your love for the game.... Oh, and it's also traditional to high-five the ball kids whenever you get a chance.''

Joe Lynch, communications manager for the ATP Tour, says the Jensens have one of the busiest schedules on the tour. ''They run clinics for kids wherever they play. They do a lot of charity work and rarely turn down any requests for helping out underprivileged children,'' he says.

More big tennis to come

ANDRE AGASSI, the No. 1 seed, and No. 2 Pete Sampras still appear headed for a final showdown at the US Open. Men's quarterfinals were being completed last night, with Sampras taking on the unseeded Byron Black of Zimbabwe and Michael Chang (No. 5) playing Jim Courier (No. 14). Boris Becker (No. 4) and Agassi have already secured positions in the semifinals. Men's semis will be played Saturday and the final on Sunday. (Both on CBS; check local listings.)

On the women's side, today's semifinals match No. 1 seed Steffi Graf with Gabriela Sabatini (No. 9). Monica Seles (No. 2) will take on Conchita Martinez (No. 4). The women's final is played Saturday. (Also on CBS.)