The world number 247, riding Oldenburg gelding Aje Cluny, was one of seven riders to go clear in the first round to force a jump-off in the American city.

Heineking then went clear again in the quickest time of 37.82sec.

This was only a fraction faster than Mexico's second placed rider Enrique Gonzalez, the winner of the third leg of the season at the Del Mar Fairgrounds who was timed at 37.83sec on board Chacna.

Tina Yates of the United States, riding Zelote VDL, was clocked at 39.50sec for third place as five riders went double clear.

"On the way from the combination to the wall, my horse was bucking a little bit, so that can be one hundredth of a second right there," said Heineking after his narrow success.

"Cluny has been with us for the past two-and-a-half years, and he developed from a nice prospect to a really competitive Grand Prix horse. 

"He just got more experience over the time and tonight was his night. 

"He keeps going better and better and is more comfortable with the height.

"I’m very excited about the win and very proud of him.

"Today’s probably [Cluny’s] biggest win to date so far."

Gonzalez leads the overall standings on 42 points, with Egypt's Nayel Nassar second on 41 and American Karl Cook third on 38.

The season will resume in Mexican city Guadalajara on January 28.

The Las Vegas leg was the fifth of the North American League Western Sub-League season, with 14 qualifying rounds in all.

The Nevada city was today awarded the rights to the finals of the FEI World Cup Jumping and Dressage in 2020, with both competitions due to be held at the iconic MGM Grand Garden Arena for the first time.