Jon Rahm credited "Ted Lasso" for his magnificent display in the opening round of the BMW Championship as the world number one and defending tournament champion earned a share of the three-way lead.

Rahm carded a flawless eight-under-par 64 to top the leaderboard by one shot alongside fellow star Rory McIlroy and Sam Burns in the second PGA Tour FedEx Cup play-off event in Maryland, Baltimore on Thursday.

At The Northern Trust, Rahm appeared on track to claim the opening FedEx Cup tournament before fizzling out as the Spaniard fell short of a play-off in Monday's finish at Liberty National.

Rahm, however, bounced back at Caves Valley Golf Club, where he invoked the "Ted Lasso" mentality – the star character of the popular television show featuring Jason Sudeikis.

"I must say, for all those 'Ted Lasso' fans out there, be a goldfish," Rahm – second in the FedEx Cup rankings – said post-round after holing eight birdies without dropping a shot. "If you haven't seen the show, you've just got to check it out.

"Played great golf last week, just a couple bad swings down the stretch, and that's the most important thing to remember."

Former world number one McIlroy, who lamented fatigue prior to Thursday's first round, opened his BMW Championship campaign with an eagle, seven birdies and a bogey.

The 2016 and 2019 FedEx Cup champion enjoyed a bogey-free front nine, highlighted by the Northern Irishman's four birdies.

Burns, like Rahm, made it through 18 holes without dropping a shot as the American tallied eight birdies, including four in a row from the 11th to the 14th.

In a 70-man field, reduced from the top 125 points leaders at The Northern Trust, Sergio Garcia is one stroke adrift of the trio, while Abraham Ancer and Patrick Cantlay – fourth in the rankings – are six under.

FedEx Cup champion and three-time tournament winner Dustin Johnson ended the day five under following his first-round 67, alongside the likes of points leader Tony Finau, Xander Schauffele and Masters holder Hideki Matsuyama.

Cameron Smith, who lost to Finau in Monday's Northern Trust play-off, is four shots behind the leaders and he is joined by Phil Mickelson, Bryson DeChambeau and 2017 FedEx Cup winner Justin Thomas.

Four-time major champion Brooks Koepka posted a two-under-par 70, while Jordan Spieth shot a 71.