Haas team principal Guenther Steiner believes the arrival of Kevin Magnussen this season has pushed Romain Grosjean.
The Dane joined Haas from Renault ahead of the 2017 campaign as a replacement for Esteban Gutierrez for the American team’s second season in the sport.
Gutierrez failed to score any points in 2016, while Grosjean finished in the top 10 on five occasions, but Haas have emerged as a stronger outfit this term.
Magnussen has already picked up 11 points in the opening 11 events of 2017 and Steiner feels the 24-year-old’s arrival has prevented Grosjean from becoming complacent.
"He reacted very well," Steiner told Autosport magazine when asked how Grosjean had initially taken the news of a change of team mate.
"I think he took it down as a challenge.
"At the beginning, he was maybe out of his comfort zone.
"But I think they get the best when they are just a little bit out of their comfort zone.
"When you are in the comfort zone you stagnate.
"You get complacent. It's very easy to get complacent if you're not challenged.
"You need always to get a little bit pushed. Otherwise if you're too comfortable, it's always too easy."