Rory McIlroy admitted that he was very pleased with his opening round at the Tour Championship as the four-time major winner sits just one shot off the lead following the first day's play in Atlanta.

The former world number one started the day on five under par under the FedEx Cup finale's new format and an opening 66 sees McIlroy move into fourth place on nine under par.

Two birdies either side of a bogey on the par-four fifth saw McIlroy turn in 34, before a flawless back nine, which included three birdies, resulted in a fine 66 as the former champion played his way into contention heading into the second day's play.

"Very pleased," said McIlroy, speaking on Sky Sports, when asked about his impressive finish.

"I hit it in the fairway a little bit more than I did last week, so it gives you opportunities to shoot at some pins.

"So to shoot three under for the back nine was very pleasing."

Opening day leader, Justin Thomas, maintained and extended his lead throughout the opening nine holes, having started the day on ten under par, moving to eleven under at the turn.

However, a stumble midway through the back nine saw Thomas make bogey and double bogey to drop back to nine under par.

A closing birdie on 18 saw the 2017 PGA Championship winner move back to ten under par and take a share of the lead alongside Xander Schauffele and four-time major winner Brooks Koepka.

Schauffele was the main mover of the day, shooting the best round of the day, a six-under 64, while Koepka shot three-under, having begun the day on seven under par.