Joel Dahmen’s profile received a heightened spotlight thanks to a weekend pairing with Tiger Woods. The 30-year-old journeyman grabbed attention for a different reason Sunday night.

In the final round of the Quicken Loans National, Dahmen was paired with Sung Kang. On the 10th hole at TPC Potomac, Kang’s second shot found the hazard. What followed was a bizarre, rarely-seen sequence on tour.

Kang believed his ball crossed the hazard, giving him a drop on the side of the hazard closer to the hole. Dahmen disputed the account, asserting Kang’s ball failed to cross. The argument continued for so long that the group behind the duo, Ben Crane and Ryan Palmer, played through.

A rules official eventually sided with Kang, as the South Korean player was allowed to take a drop on the side of the hazard closer to the hole. He would save par on the 10th and turned in a six-under 64, a score that translated to a T-3 finish that earned him an invite to the 2018 Open Championship.

Dahmen, however, continued to feel Kang’s drop was unjust, airing his grievances on Twitter Sunday night.

When asked why Palmer and Crane played through, Dahmen was blunt: “Kang cheated. He took a bad drop from a hazard. I argued until I was blue. I lost.”

This accusation quickly drew follow-up inquiries on the matter, and Dahmen was happy to oblige. “It was a typical dispute about where or if it crossed the hazard,” he said. “It clearly did not cross the hazard. We went back and forth for 25 minutes and he ended up dropping closer to the green.”

In spite of his protest, Dahmen said he had to sign the card. “At that point there is nothing I can do. If I don’t sign the card, a rules official will. I would just be delaying the inevitable.”

Dahmen’s caddie Geno Bonnalie backed up his player, and confirmed the argument on the 10th. “We didn’t agree on the spot where it ‘crossed,'” he said.

Though the Rules of Golf 26-1/15—Procedures for Relief from Lateral Water Hazard allow a player to drop from the last point where the ball rolled into the hazard, Dahmen maintains 26-1/21—Example of Serious Breach of Lateral Water Hazard Rule was at play. But unless video proves Kang wrong, the ruling from the official that allowed Kang to take his drop stands.

The PGA Tour and Dahmen’s representatives have not yet responded to comment on the accusation, while attempts to reach Kang proved unsuccessful. Dahmen, a cancer survivor, has made 14 cuts on tour this season.