Thomas and good friend Jordan Spieth became investors last summer after being converted into Leeds fans by English golfer Matt Fitzpatrick’s caddie Billy Foster.
“We’ve definitely become a lot closer over the last year, and he’s given us a lot of insight and knowledge in terms of Leeds and sending us videos from games,” said Thomas.
“I like the fact that they’re playing at Elland Road. I know that they’re a tough team to beat there, so I’m excited to watch.”
Leeds, who have failed to gain promotion from all five of their previous play-off attempts, drew the first leg 0-0 at Carrow Road.
The winner will face West Bromwich Albion or Southampton at Wembley for a place in the Premier League.
Thomas was at Valhalla as a seven-year-old fan when Tiger Woods won the US PGA in 2000. He had turned professional by the time it returned in 2014, but missed out on qualification.
“Watching Tiger here in 2000 in person is a large part of my love for professional golf and wanting to win majors and golf tournaments,” he said.
“I obviously don’t remember a lot, being seven years old. But just hearing the roars – you’re on one side of the course, you hear it on another side of the course – that’s pretty cool to hear.
“How it all ended and me being a Tiger fan, it was about as perfect a week as I could have imagined.”
To have a perfect week this week for himself, Thomas will need to find the form that lifted him to the 2022 US PGA title at Southern Hills.
He was ranked fifth in the world after his second major triumph but is now 31st and enduring another inconsistent season on the PGA Tour with three top-10s in 2024 offset by three missed cuts in his past seven events.
In seven majors since his victory, Thomas has missed four cuts and failed to finish inside the top 35 in the other three.
He can expect huge home support, though.
“I played nine holes with him [on Monday],” said Ryder Cup team-mate Spieth, who has won The Open, US Open and Masters and is aiming to beome the sixth player to complete a career Grand Slam.
“It felt different. There was a massive amount of support for him already, and I know that will continue as the week goes on.
“If there’s one tournament this year that he would want to win, it would be this one, and it would be one of the coolest moments of his life.”