Rory McIlroy sits inside the top 20 at the CJ Cup @ Summit, however, the former world number one is seven shots off the lead after the opening round in Las Vegas.

McIlroy shot four under to open at the PGA Tour event, however, it could have been so much better only for a triple bogey on the penultimate hole in Nevada.

The four-time major winner opened with a birdie on the first and added another on the sixth to reach the turn on two under.

But it was an unorthodox back nine as McIlroy went birdie-bogey-birdie to start before picking up three shots on the 14th and 15th with an eagle and birdie on the respective holes.

Heading down the 17th hole on six under, which would have put McIlroy inside the top five, he made a seven on the par four, however, he did pick up a shot on 18 to at least limit some of the damage.

"It was really good apart from one bad swing, I missed the three wood on 17, right and messed around in the rocks and ended up with a seven," said McIlroy.

"If you keep it in play, it's very scoreable, but if you hit a couple off line and you get a bad break, you can get a big number. I did that on 17, but the other 17 holes were really good."

American Robert Streb shot an impressive 61 to get to 11 under, and leads by one shot, with compatriot Kevin Mitchell on ten under par. Hudon Swafford makes it a USA 1-2-3, as he sits on seven under in third place.

Ian Poulter is the best of the Europeans, as the Englishman shot a flawless 66, turning on three under, before adding three more birdies on the way in.

Shane Lowry, meanwhile, sits in a tie for 69th following a disappointing one-over 73.