Daniel Ricciardo was running in ninth place and hopeful of picking up a couple more championship points for Toro Rosso, when suddenly his race came to a premature end three laps from the finish of the Korean Grand Prix.
"There was a mechanical problem at the front left corner," revealed Ricciardo when he got back to pit road.
His team mate Jean-Eric Verge was also told to retire by the pit wall seconds later, indicating that whatever the problem was it was an shared issue with both Toro Rossos on Sunday.
"At the moment, we're not quite sure what happened in the end," Vergne admitted. "I felt the car pull to one side and something was clearly not right, so the team called me into the pits."
Team principal Franz Tost was also tight-lipped: "We had a mechanical issue on [Daniel's] car which we will investigate when we get it back and he had to park at the side of the track," he said. "In the end we had to retire [Jev] with what might be a similar problem to Daniel's car."
Subsequent reports added only that an overheating part on the car had resulted in a mechanical issue. It was unfortunate for both men, and especially for Ricciardo who'd been on course for a better-than-expected result from 12th on the grid after gambling on starting on the medium tyres - the only driver on the grid not on the supersofts.
"Personally, I was really pleased with my performance in the car today," he said. "Maybe we didn't have a top ten car but I was able to fight in the top ten. For myself and the team it's frustrating to get no reward.
"I think we did all we could today in the race," he continued. "I had a decent first stint and tried to run as long as possible on the prime tyre. The car wasn't perfect but it was good enough to be in a points position with a few laps to go and I was hanging on nicely to ninth."
Vergne had a bigger handicap after qualifying in 16th place, which he admitted was always going to make things difficult for him to retrieve any positives from the weekend.
"After I made up a few places in the early stages I began to suffer with tyre degradation, so I agreed when the team decided to switch me from a two to a three stop strategy," he explained.
"I just want to get to Suzuka and start again now, but we will need to do a lot of work if we want to return to the performance level we should have had here," he added.