When it come to sad sack B-day bashes LISA MARIE PRESLEY’s rodeo has left the building, say sources.

LISA MARIE PRESLEY’s 45th birthday bash should have been a happy, heel-stompin’ hoedown, but a pre-party blowout with her hubby, Michael Lockwood, ruined the rodeo for the rock ’n’ roll heiress – and she spent most of the night knocking back the booze!

More than 60 guests turned out to celebrate the spe­cial occasion at the Saddle Ranch Chop House – a popular, cowboy-themed bar and restaurant in Universal City, Calif. – on Feb. 1. But the festive mood was nearly poisoned by the tension between the birthday girl and her man after they showed up nearly an hour late to the event.

“MICHAEL SPENT A LOT OF TIME planning every detail of the party, and he was furious that Lisa Marie took so long getting dressed that they were an hour late,” said a pal. “They had a huge argument and ended up ignoring each other the whole night.”

The couple strolled into the event hand-in-hand, the pal said, but they quickly went their separate ways. Lisa Marie – who looked stunning and far younger than her years in a backless, long-sleeved black dress accented by a red belt – spent the remainder of the evening drinking champagne… and avoiding her husband!

According to insiders, Michael, 41, had gone to great lengths to throw the perfect party for his wife, sending out Wild West-themed party “evites” and arranging a menu that included her favorite dish, jalapeno macaroni and cheese.

“There were gorgeous buffet-style tables heaping with barbecue deli­cacies, but I didn’t see Lisa Marie take a bite of food all night,” divulged one partygoer. “She downed glass after glass of Dom Peri­gnon as she mingled with guests.

“Lisa Marie put on a happy face, but it was apparent to anyone who knew her that she was very upset with Michael.”

Fortunately, revelers didn’t let Lisa Marie and Michael’s bickering spoil the shindig. They kicked up their boots and enjoyed the pool table, me­chanical bull, private bar and large TV screens that were showing the 1977 Burt Reynolds film “Smokey and the Bandit.”

The disc jockey played songs specially chosen by Michael for Lisa Marie.

“Lisa Marie didn’t join her guests in any of the activities, like shoot­ing pool or riding the mechanical bull,” confided another source. “She just quietly sipped her champagne – downing five glasses throughout the evening – and talked to friends.”

The source added that Lisa Ma­rie hung out at the bar with rocker Melissa Etheridge for most of the night, but she also spent time with her mother Priscilla and Priscilla’s current boyfriend, “American Idol” producer Nigel Lythgoe.

Meanwhile, “Michael sat sullen at a table with a few pals.”

Shortly before mid­night, guests gathered around a pool table and sang “Happy Birthday” as Lisa Marie made a wish and blew out the candles on an elegant cake decorated in black and white fondant.

As the party came to a cli­max, guests danced to her favorite song, “Hollywood Swinging,” by Kool & the Gang.

Lisa Marie and Michael, who cel­ebrated their seventh anniversary on Jan. 22, left the bash together a little before 2 a.m., “but they didn’t seem happy about going home together,” said the pal.

THIS ISN’T THE first time the union has shown signs of stress. The relationship was on the brink of collapse last summer after her latest album, “Storm & Grace,” came out. For months before its re­lease, the couple had battled over everything from Lisa Marie’s single-minded focus on her music career to how best to raise their 4-year-old twin daughters, Harper and Finley.

Like her famous father Elvis Presley, Lisa Marie also has a history of substance abuse problems. Although she has said that those troubles were isolated to her teen years, sources say Lisa Marie is a big wine drinker.

In a 2003 interview with “Play­boy,” the entertainer admitted she’s “friendlier, nicer, more tolerant and more patient” after imbibing.

“I was at a party she had last year at Chateau Marmont in Hol­lywood, and she looked hammered after drinking champagne all night,” added the source. “She didn’t appear nearly that bad off at her birthday party, but she definitely had her share of the booze.”