Dustin Johnson and Bryson DeChambeau have committed their futures to the PGA Tour, delivering potentially fatal blows to the prospects of a breakaway golf league.

The Ryder Cup team-mates have joined the likes of Rory McIlroy, Tiger Woods, Jon Rahm, Collin Morikawa, Justin Thomas and Brooks Koepka in resisting the overtures of a Saudi-backed rival circuit spearheaded by Greg Norman.

In a statement released by the PGA Tour, Johnson said: “Over the past several months, there has been a great deal of speculation about an alternative tour; much of which seems to have included me and my future in professional golf.

“I feel it is now time to put such speculation to rest. I am fully committed to the PGA Tour.

“I am grateful for the opportunity to play on the best tour in the world and for all it has provided me and my family.

“While there will always be areas where our Tour can improve and evolve, I am thankful for our leadership and the many sponsors who make the PGA Tour golf’s premier tour.”

Four hours later, DeChambeau wrote on his official Twitter account: “While there has been a lot of speculation surrounding my support for another tour, I want to make it very clear that as long as the best players in the world are playing the PGA Tour, so will I.

“As of now, I am focused on getting myself healthy and competing again soon. I appreciate all the support.”

DeChambeau withdrew from the Saudi International after an opening 73 earlier this month, citing hand and hip injuries.

The announcements from Johnson and DeChambeau came three days after Phil Mickelson’s motives for potentially joining a breakaway league were laid bare in an extraordinary extract from a new biography of the six-time major winner.

The 51-year-old admitted the threat of a new league has given the players leverage to squeeze more money out of the PGA Tour, and said he is not even certain he wants the breakaway to succeed.

In an interview with Alan Shipnuck for his forthcoming book, ‘Phil: The Rip-Roaring (and Unauthorized!) Biography of Golf’s Most Colorful Superstar’, Mickelson also claims the new league is an attempt at “sportswashing” by the Saudi regime.

Mickelson admitted he has concerns about Saudi Arabia’s human rights record in a telephone interview with Shipnuck last November, adding: “They’re scary mother******* to get involved with.

“Knowing all of this, why would I even consider it? Because this is a once-in-a-lifetime opportunity to reshape how the PGA Tour operates.

“The Tour likes to pretend it’s a democracy, but it’s really a dictatorship. They divide and conquer.”