Daniel Ricciardo's right rear brake problem in the Russian Grand Prix was "very strange", says Red Bull Formula 1 team principal Christian Horner.
Ricciardo was running seventh just after the restart from the early safety car period at Sochi when he noticed his right rear brake was on fire and slowed.
Red Bull instructed him to bring the car back to the pits gently, and then retired it after an inspection.
It comes after team-mate Max Verstappen crashed out of the Bahrain GP a fortnight ago when he suffered a brake problem on an out-lap.
Horner said the team would investigate Ricciardo's problem and early indications suggested it was a different issue to Verstappen's at Sakhir.
"It's similar outcome but different issue so we need to understand the cause of it," Horner told reporters after the race.
"We've got a bunch of bits at the moment so there needs to be a full investigation as to what caused the issue.
"Was it a touch at the second turn, was it something else, because after the restart immediately the component has failed.
"Everything before seemed under control so it was absolute sudden failure.
"It's just very strange to happen immediately after the restart."
Ricciardo added: "It was early in the race so I don't know how much the safety car and two starts impacted us but the team will obviously investigate that.
"It's frustrating, on a Sunday you just build up for the race and try to store up your adrenaline to use at 3pm but today it was over very quickly."
Red Bull instructed Verstappen to wind his brake balance forward after the incident, but Horner said that was just a precaution.
"There were no issues with Max through the race," said Horner.
"We were just taking a precaution to take a bit of energy out of the rear brakes."
Verstappen finished the grand prix a lonely fifth, comfortably ahead of the Force Indias but over a minute adrift of winner Valtteri Bottas's Mercedes.
"I thought Max actually drove a very good race, very disciplined," said Horner.
"His pace in the second half of the race was more respectable.
"He got everything he could out of the car today."