Daniel Ricciardo and Max Verstappen's relationship away from the Formula One paddock is helping their performances on the track, says Christian Horner.
The pair have flourished since being brought together at Red Bull ahead of the Spanish Grand Prix, Verstappen having replaced the demoted Daniil Kvyat.
Verstappen claimed victory in his first race in Barcelona and had a season-long fight with his team-mate as Red Bull led the charge to catch Mercedes.
In the end it was Ricciardo who edged the battle by 29 points, while he out-qualified Verstappen 11 times to six.
Horner has been pleased with the respectful battle the pair had across the 2016 season and is also delighted to see them get on out of the car.
"The most important thing is there is respect," Horner told Autosport. "We don't ask drivers to go out to dinner with each other but ask that they respect each other and respect the team.
"The two have done exactly that and the fact that their relationship goes beyond that is only a benefit to us.
"Daniel in many ways has almost been like an older brother to Max.
"Their feedback is very similar, the demands from the car are very similar.
"Very often when you're listening in, in qualifying or the race, the comments about the car are almost identical so for the designers and R&D guys it's a great scenario to have both drivers chasing the same thing."