Webb Simpson and longtime caddie Paul Tesori have split after a dozen years together.

Simpson announced Tesori’s departure from his team via social media on Monday. He said Tesori is moving to the bag of 25-year-old Cameron Young.

“This was an incredibly difficult decision for both of us, but one that we have thoroughly considered after spending many hours in prayer, seeking counsel from mentors, and having countless conversations together,” Simpson tweeted.

With Tesori by his side, Simpson won the 2012 U.S. Open and the 2018 Players Championship. They were together as Simpson ascended to No. 4 in the world golf rankings and also at multiple Ryder Cup and Presidents Cup events.

“Our time together has been truly unforgettable. … I could never have done this without Paul by my side.”

Simpson, 37, last won in 2020 at the RBC Heritage. He didn’t announce in his post who will assume the role as his caddie.

Simpson has battled a variety of ailments, including a neck injury, over the past few years. His best finish of the season came Sunday, when he tied for seventh at the Valspar Championship.