Jordan Spieth started to go there with Phil Mickelson, but he stopped mid-answer.

Speaking to reporters Friday at TPC Southwind, site of the FedEx St. Jude Championship in Memphis. Tenn., Spieth was asked how the PGA Tour locker room reacted to the bombshell claims that Mickelson had gambled $1 billion on sports over 30 years.

He started to give an honest answer before catching himself mid-sentence and pleading ignorance.

“I would say people were maybe a bit surprised at the amount of … I haven’t really seen a whole lot on it. I just saw what some people sent me and stuff, and it was so quick this morning that even if I wanted to comment I don’t think it’s a good idea,” Spieth said.

The numbers on Mickelson’s betting habits came out via a book by his former gambling partner, Billy Walters, whose memoir “Gambler: Secrets from a Life at Risk” comes out Aug. 22.

Walters said in the book that between 2010-14 alone Mickelson wagered $110,000 to win $100,000 more than 1,110 times, and $220,000 to win $200,000 almost 900 times.

Just those bets alone totaled more than $300 million.

“Based on our relationship and what I’ve since learned from others, Phil’s gambling losses [between 2010 and 2014] approached not $40 million as has been previously reported, but much closer to $100 million,” Walters writes.

Walters also claimed that Mickelson asked him to put down a $400,000 bet on the U.S. team he represented in the 2012 Ryder Cup, a request Walters said that he denied.

In a statement released Thursday, Mickelson denied wagering on the Ryder Cup

“I never bet on the Ryder Cup. While it is well known that I always enjoy a friendly wager on the course, I would never undermine the integrity of the game,” Mickelson said.