PARIS— It is rare, if not unheard of, for a president of France to be upstaged at his own inauguration. But when Cecilia Sarkozy, a former model, swept up the red-carpeted steps of the Elysée Palace yesterday, the new first lady stole the show from husband Nicolas.

Mrs. Sarkozy looked more like a star arriving at the Cannes Film Festival than the matronly presidential consorts France is accustomed to. Camera shutters whirred as the 49-year-old, holding the hand of their 10-year-old son, Louis, brought Jackie Kennedy glamour to proceedings in an ivory duchess satin Prada dress. Known to prefer T-shirts, combat trousers, and cowboy boots, Mrs. Sarkozy silenced at a stroke the critics of her dress-down style.

Her husband won the French presidency with a promise of change. The sight of his two sons from his first marriage and Cecilia’s two daughters by her first husband posing together with Louis was a striking illustration of how French society had evolved since Jacques Chirac took office 12 years ago.

Tanned from his short break on a billionaire friend’s yacht in Malta, Mr. Sarkozy, 52, dressed in a dark Prada suit, was welcomed to his new 365-room office by the man for whom it has been home for the past 12 years. Mr. Sarkozy struggled to adopt the customary slow presidential walk as he marched past Republican Guards. There to greet him was the perma-tanned Mr. Chirac, an unrufflable smoothie who towered over his diminutive successor.

Mr. Sarkozy appeared oddly ill at ease as the outgoing president guided his inexperienced successor up the steps. Mr. Sarkozy tried to regain the advantage by placing his hand on Mr. Chirac’s shoulder, but the choreography failed to work.

The body language spoke volumes about the tension that has characterized the two men’s relationship over the past three decades, despite efforts to bury their differences in the final weeks. The pair then spent half an hour in a private meeting in which the new president received the nuclear codes that permit him to launch a strike within a minute.

Mr. Sarkozy’s speech was heartfelt, if punctuated by nervous tics and shoulder shrugs that betrayed what his enemies claim is a worrying lack of self-control.

Mr. Sarkozy’s mother, Andrée, sat in a throne-like chair. His once estranged father, Pal, a minor Hungarian aristocrat, was also present. He is believed to have been reunited with his son only very recently. His desertion of the family and reported warning to little Nicolas that he would never amount to much is said to have sparked his son’s burning ambition.

After the pathos, the passion: Mr. Sarkozy planted a kiss on the lips of Cecilia — whose absence during the campaign had fueled rumors that the couple was going through fresh marital problems — and gave her cheek an affectionate squeeze. Then, under the glare of the cameras, it was her turn to surprise him with kiss on the lips. It is not known whether Cecilia and the children will move into the Elysée Palace with her husband.

“I don’t see myself as a first lady. It bores me. I’m not politically correct,” she once said.