Sergio Perez reckons his former Sauber Formula 1 team-mate Kamui Kobayashi is an "amazing" rival who taught him vital lessons in how to manage tyres.
Perez raced alongside the Japanese driver at Sauber for his first two seasons in Formula 1 in 2011-2012, before moving to McLaren.
The Mexican has gained a reputation for excellent tyre management during his time in F1, allowing him to often stop fewer times during races than rivals.
Perez, who utilised such a strategy to finish an unlikely sixth in June's Austrian Grand Prix for Force India, said he owed much of this reputation to skills learned during his early campaigns alongside current Caterham driver Kobayashi.
"Kobayashi was really, really difficult to beat," Perez told AUTOSPORT.
"When he felt comfortable he was definitely one of the most difficult ones to beat, especially over a single lap.
"He was really amazing. I learned a lot from him on how to work with the tyres.
"He has a good experience with the Japanese, they are always good on tyres.
"That was good for me to learn from him."
Perez has been comprehensively outscored by Force India team-mate Nico Hulkenberg across the first 11 races of the current campaign.
Hulkenberg had finished 12 consecutive races inside the points before crashing out of the recent Hungarian GP, and Perez said the German's driving had helped him raise his own game.
"Nico is a very strong team-mate - definitely one of the strongest I've had," Perez added.
"He is very complete and that helps me to go to another level.
"From every team-mate I learn things, and it's good when you have different team-mates in different teams, it helps you with your experience for the future."