That would be Phillies manager Charlie Manuel.
Manuel was Thome's mentor as a young hitter, the man most responsible for developing Thome into one of Major League Baseball's most feared sluggers -- now a certain first-ballot Hall of Famer. He needs just 11 homers to reach 600.
Of course that honor will come only after Thome retires, and considering the way he's performing at age 40, it's not any time soon.
With a hot sun beaming down, Manuel and Thome stood on the first-base line and talked for more than 20 minutes.
"I wanted to get up here early so I could spend some time with Chuck and my friends on the Phillies," said Thome, who spent three seasons with the Phillies before being traded to the Chicago White Sox to make room at first base for Ryan Howard.
"I look at Jimmy as a son," says Manuel. "When I see him, I keep telling him he's my son."
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Pausing, Manuel adds: "One reason for that is because he can hit. Really hit. If he couldn't hit, maybe I'd look at him as a nephew or something!"
Said Thome: "I often think back to the years I was with Charlie when he worked with me in the Minors as a hitting coach and when he was managing the Indians [2000-02]. There were a lot of ups and downs, a lot of grinding it out.
"He's a very good baseball man in all aspects. He can pick out the little things in your swing and work on them with you. He has that special knack."
A year ago, Thome had just signed a free-agent contract with the Twins, and although he immediately sensed the clubhouse atmosphere and the players were special, he had no idea what to expect.
Thome even mentioned that it's difficult for a player to know when his career is coming to an end. Or should.
That talk doesn't even enter his mind these days, although he stretches and had treatment for a chronic lower back problem each day. He gave the Twins a veteran presence and helped them win their sixth American League Central title in nine years.
Along the way, he blasted a team-high 25 homers and batted .283 as a designated hitter.
"He brings the same enthusiasm to the ballpark every day," says manger Ron Gardenhire, who's challenged this season to mold a team with a myriad of new faces. "He's great for our young guys. He keeps the game very simple, yet he works very, very hard to be prepared. Whether he's playing or not Jim Thome is an unbelievable presence."
Injuries to other players in 2010 made Thome, who signed a one-year $1.5 million deal, even more valuable to the Twins. He was the everyday DH for more games than he expected.
This year, with first baseman Justin Morneau back -- he went on the disabled list last July 8 -- Michael Cuddyer will move to right field, with Jason Kubel, who played in right last year, the primary DH.
"Last year, we just knew we had a guy we wanted for a long time," says Gardenhire. "We had high respect for him, watching him play against us. We needed somebody in case someone else got hurt or on those days when we wanted extra at-bats from a DH -- the type of guy we haven't had in a long time. When Morneau went down, Thome was a life-saver."
Thome was a free agent again this offseason, and after considering an offer from the Texas Rangers, returned to the Twins for $3 million.
"I really wanted to come back," he says. "It really wasn't about the money. I made the decision to come back here for what I consider the right reason."
The Twins have won all those division titles, but were swept in 2010 by the Yankees -- the fifth straight time they've been ousted in the first round. They haven't been to the World Series since 1991.
With Morneau, et al, back Thome enters the season in pretty much the same role promised him in 2010.
"We do have a lot of changes this year," says Gardenhire. "We lost our whole bullpen and have a whole new middle infield. That's going to be difficult. Today, this is not a finished product by any stretch of your imagination."
"I really never felt like I was a backup," Thome says. "Gardy gets all his guys in the game. He rotates out the lineup and gets everybody in there."
When Thome reaches 600 home runs, he'll become only the eighth player in history to join that club -- and the oldest.
"I'm trying not to think about it," he says. "The thing is you just have to go play and try to win. All that other stuff will take care of itself."
As Thome spoke, fans hanging over the Twins' dugout yelled his name, asking for autographs.
Calmly, he walked over to the fans and obliged. For me, that brought back a memory when his real dad, Chuck, recalled a day at Chicago's Wrigley Field when Dave Kingman refused to give 10-year-old Jim Thome an autograph.
"He vowed to me that day if he ever made the Major Leagues, he'd never do that to a fan," Chuck said.
Now, Thursday's game was in the first inning and Thome, batting cleanup, ripped a double off Phillies lefty Cole Hamels.
Manuel, watching from the Phillies dugout, tried not to smile, but deep down he had to feel good.
There's nothing like a "son" who can hit.
Hal Bodley is the senior correspondent for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.