The sprint for the line came from a reduced group after a crosswind section split the peloton with 15 kilometres to go.
With many riders caught out, including the top sprinters, the odds for Edvald Boasson Hagen (Dimension Data) and Degenkolb looked good, but in the final metres ahead of the line, Matthews (Sunweb) snatched his second win of this Tour, leaving the former taking second and latter fuming in third.
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"Matthews did not hold his line in the sprint, and that cost me the chance for victory today," Degenkolb said.
"I was on his wheel, in the perfect position to launch the sprint at 200 metres, and I started the sprint. I clearly came with more speed from his wheel, and he saw me on the right side and closed the gap on the right side. It made me stop the sprint, stop sprinting for the victory.
"I felt like I had the legs to win today. It was very clear he went off his line into my line. In the heat of the situation, you are immediately angry if the chance for a win has been taken away when you know you have the legs to overtake him. It's very disappointing."
Trek-Segafredo did not file an official protest and left it up to the race jury to decide if it was enough to flag as foul. The decision was swift, and Matthews was declared the winner but only after Degenkolb had lashed out at a perplexed Matthews.
"He grabbed me by the neck. The officials saw that. I don't know what they're going to do about it," Matthews said. "It was not very sportsmanlike.
"From my perspective, I didn't do anything wrong. I started my sprint and sprinted in a straight line. I don't know what's wrong with him, but that's up to him.
"If I had done anything wrong the race officials would have told me."
From the TV replays, it did appear Matthews had moved sightly off his line, but it was also evident that Degenkolb had enough room to respond.
However, Trek-Segafredo General Manager Luca Guercilena was adamant that at well over 60km/h, even a small movement is amplified and was enough to disrupt Degenkolb's sprint.
"Probably from the images it was clear he had enough room, and we have to respect their decision, we are not here to make more stress for this kind of situation. But we also understand the side of John and that he probably had the power, but he felt the risk of being closed into the fence. For the Jury that is not the case, and that's the end of the story,” said Guercilena.
Boasson Hagen accepts defeat in his second photo finish of the Tour
Boasson Hagen has twice now been in a photo finish at the Tour de France but this time he knew he was beat.
Matthews and the Norwegian both threw their bikes at the line in Romans-sur-Isere leaving officials to briefly adjudicate the result.
Boasson Hagen lost Stage 7 to Marcel Kittel by five millimetres, one of the Tour’s closest finishes, but Boasson Hagen didn’t need to wait for officials today.
“I thought I was second when I crossed the line so I was surprised it was actually a photo finish. “He’s strong. Everyone knew he was going to be up there I think.” - Edvald Boasson Hagen
Boasson Hagen opened his sprint early, having to make up about six positions he lost coming into the last corner after the aggressive day in crosswinds.
“It was a hard stage but the team did really well to keep me up the front the whole day. I was just a bit too far back in that last corner, I knew I had to be at the front there but sometimes this happens. I almost made it, it’s a pity I didn’t make it,” he said.
The 30-year-old has now featured in the top three of four stages and has perhaps one more chance in Salon-de-Provence on Friday to break through.
“I feel I’ve been up there quite a lot, but motivated that the team did really well. I’m happy for the team for the work they did. We just have to keep fighting. There are still some stages left,” he said.
