Prince Harry sported the stars and stripes on his cap Sunday as he left San Diego's Andaz Hotel, where he spent the weekend partying at the establishment's in-house nightclub, Ivy Rooftop.

As we previously reported, the red-headed royal and about 20 pals were spotted Friday at the nightspot, where they sipped on Absolut Vodka, Red Bull and beer, before taking to a private cabana to watch a rugby match until the wee hours of the morning.

Of course, it's a trip of business and pleasure for the prince, who's in Southern California to prepare for the final phase in his training as an Army Apache pilot.

He hasn't even been in the U.S. for a week, but Prince Harry has already had himself a night on the town.

The Prince and 20 of his pals were spotted Friday at Ivy Rooftop, the hip nightspot atop Andaz San Diego.

The group ordered Absolut Vodka, Red Bull and beer, and enjoyed the views of downtown San Diego. By midnight, they moved to the rooftop’s pool deck and from a private cabana, watched the rugby match and celebrated until the early hours of the morning.

PHOTOS: Prince Harry Turns 27

Prince William's younger brother is stationed at a military base in El Centro, Calif., about 90 minutes from San Diego. He'll be there for two months training in the fine art of live firing from an Apache attack helicopter.

Prince Harry arrived at the Naval Air Facility in El Centro, California on Thursday, as he prepared for the final phase in his training as an Army Apache pilot, and RadarOnline.com has the first pic of the red headed royal.

The facility is about 110 miles east of San Diego (where much of the iconic 80s film Top Gun was shot); after his stint there, the 26-year-old prince will head to Gila Bend in Arizona to train at the Air Force Auxiliary Field.

The trip is part of the two-month training mission dubbed Exercise Crimson Eagle, in which British fliers will practice with the Apaches in terrain similar to southern Afghanistan, where some British troops are currently based. During his trip, Harry will use live fire for the first time in his helicopter gunship training.

Following Prince William and Kate's high-profile trip to California last June, Prince Harry is coming to America this week.

While the Duke and Duchess of Cambridge's visit was dominated by strict social engagements, Harry's will be for work -- and no doubt plenty of play!

The youngest Prince is coming to the U.S. as part of an Apache attack helicopter training course conducted by Britain's Defense Ministry at the Naval Air Facility El Centro in California, about 90 miles east of San Diego.