Tiger Woods won his superstar grouping with Rory McIlroy and Justin Thomas – but shared a chat about football and baseball during the opening round of the US PGA.

The reigning Masters champion carded a two-under 68 in the first Major of the season to trail clubhouse leader Jason Day by three strokes.

Justin Rose was a shot off the lead along with defending champion Brooks Koepka after a superb short-game display saw him card a 66.

McIlroy, who started with an early hat-trick of bogeys, recovered to shoot level par 70 while world No.1 Thomas made two double bogeys on his back nine in his 71.

The US PGA is being played behind closed doors at Harding Park but the unusual lack of big-match atmosphere does allow on-course mikes to pick up conversations between the players.

Woods and McIlroy in discussion as they walk towards the fairway on the 10th hole
Woods and McIlroy in discussion as they walk towards the fairway on the 10th hole

And Woods and McIlroy talked sports on the fourth tee when the American said there was no way he would have a TaylorMade golf bag in the cream, orange and black colours of the local San Francisco Giants baseball team.

The Los Angeles Dodgers fan said: “Giants’ colours, couldn’t do it,” Woods said.

When McIlroy admitted he was not a baseball expert, the American asked the Manchester United fan which football team he supported.

Woods plays a shot from the third tee during the first round
Woods plays a shot from the third tee during the first round

“So, Liverpool, it would be like having Liverpool colours on your bag,” Woods said. “That’s how much we hate the Giants. I wouldn’t do it.”

Woods, who wore a snood during the opening holes on a cool, overcast day, hit 12 greens out of 18 in only his second event since February while using a new putter.

It was his lowest opening round in a Major since 2012.

“I have been messing about with the putter for the best part of a year," Woods, 44, said. "It is a little bit longer than the other one so it is better for my back.

"As the guys on the Seniors Tour know, as you get older, it is more difficult to bend over.”

Rose said: “I was happy to be able to birdie three of my last six holes and post a great round.”