Kevin Magnussen believes Haas team mate Romain Grosjean represents a good benchmark for the Dane to measure his relative performance.
Magnussen leads the Frenchman by just a single point in the championship standings, having achieved his best result in Azerbaijan with a seventh-place finish.
The pair are equally matched in qualifying although the Dane has yet to reach Q3, which his team mate has managed three times this season.
Still, Magnussen holds Grosjean in high regard, and reckons that on his day he is as fast as Jenson Button with whom the Dane was paired at McLaren in 2014.
"He's got everything I need from a teammate," Magnussen said of Grosjean.
"Raw speed, so I can compare and learn from him, and he's got experience as well.
"So for me he is a very good teammate - perhaps on his day faster than Jenson, but Jenson was very consistent."
Magnussen admitted that his current context at Haas provides a better environment for improvement than McLaren or Renault.
"You only have your teammate to compare and to show yourself and prove yourself [against]," he added.
"It's much better having a proven teammate who has a good reputation and is known to be very quick, so it's good to have him [Grosjean]."