Ferrari team principal Mattia Binotto has conceded reliability issues are becoming a cause for concern in the battle for the F1 titles with Red Bull.
Red Bull's reliability caused alarm in the opening three races due to three retirements between Max Verstappen and Sergio Perez, allowing the Scuderia to pull out an early advantage in the constructors' standings.
For Ferrari, Charles Leclerc lost a comfortable lead in the Spanish Grand Prix due to mechanical issues, whilst customer teams Alfa Romeo and Haas have also had to battle against unreliability.
"Reliability is always a concern," insisted Binotto. "When something is happening, it's never great. So it's worrying us. We are looking at what happened.
"Sometimes you've got straight explanations. It can be caused by external accidents. It can be caused by exceptional, let me say, circumstances. Other ones may be a true worry and concern.
"So reliability has been a key factor so far in the championship because we failed in Spain, and for Red Bull as well, they’ve got three DNFs. As you said, our customer teams got some as well.
"So it's a challenge, as performance reliability is certainly a big challenge and reliability, when you've got concerns, it's never obvious to fix them in a short time
"So yes, it is a concern."
But referring to Red Bull's issues, which stretched to problems with the DRS in Spain, Binotto added: "It doesn't mean that we are too concerned - I hope Christian [Horner] is more than myself.
"But let's do our best job from now to the end of the season and hopefully everything will be smooth and clear."